Danfoss H1 078 User manual

Service Manual
Axial Piston Pumps
H1 - 069/078, 089/100, 115/130, 147/165,
210/250
www.danfoss.com

Revision history Table of revisions
Date Changed Rev
May 2018 add angle sensor 0308
January 20187 add seal carrier to shaft repair topic 0307
February 2017 minor edit - shaft repair illustration 0306
January 2017 minor edit 0305
September 2016 minor edits 0304
July 2016 minor edits 0303
January 2016 minor edits 0302
July 2015 add 210/250 0300
September 2014 Danfoss layout - add MDC BA
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
2 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

Introduction Overview..............................................................................................................................................................................................5
Warranty.............................................................................................................................................................................................. 5
General instructions........................................................................................................................................................................ 5
Remove the unit..........................................................................................................................................................................5
Keep it clean..................................................................................................................................................................................5
Replace all O-rings and gaskets............................................................................................................................................. 5
Secure the unit.............................................................................................................................................................................5
Safety Precautions............................................................................................................................................................................5
Unintended machine movement..........................................................................................................................................6
Flammable cleaning solvents.................................................................................................................................................6
Fluid under pressure..................................................................................................................................................................6
Personal safety.............................................................................................................................................................................6
Symbols used in Danfoss literature............................................................................................................................................7
Design...................................................................................................................................................................................................7
The System Circuit............................................................................................................................................................................8
Operation Pressure Limiter Valves................................................................................................................................................................ 11
High Pressure Relief Valve (HPRV) and Charge Check......................................................................................................11
Bypass Function..............................................................................................................................................................................12
Charge Pressure Relief Valve......................................................................................................................................................12
Electrical Displacement Control (EDC)...................................................................................................................................13
Manual OverRide (MOR)..............................................................................................................................................................14
Manual Displacement Control (MDC) ....................................................................................................................................15
MDC Torque................................................................................................................................................................................16
Operating parameters Input speed...................................................................................................................................................................................... 18
System pressure............................................................................................................................................................................. 18
Servo pressure.................................................................................................................................................................................18
Charge pressure..............................................................................................................................................................................19
Charge pump inlet pressure...................................................................................................................................................... 19
Case pressure...................................................................................................................................................................................19
External shaft seal pressure........................................................................................................................................................19
Temperature and viscosity......................................................................................................................................................... 20
Technical Specifications Overview........................................................................................................................................................................................... 21
General Specifications..................................................................................................................................................................21
Physical Properties.........................................................................................................................................................................21
Operating Parameters .................................................................................................................................................................22
Fluid Specifications....................................................................................................................................................................... 22
Fluid and Filter MaintenanceFluid and Filter Recommendations......................................................................................................................................... 23
Pressure Measurements Port Locations and Gauge Installation...................................................................................................................................24
Initial Startup Procedures General ..............................................................................................................................................................................................26
Start-Up Procedure........................................................................................................................................................................26
Troubleshooting Overview........................................................................................................................................................................................... 27
Safety Precautions......................................................................................................................................................................... 27
Electrical Troubleshooting..........................................................................................................................................................27
System Operating Hot..................................................................................................................................................................27
Integral Filter Bypass.....................................................................................................................................................................28
Neutral Difficult or Impossible to Find................................................................................................................................... 28
System Will Not Operate in Either Direction........................................................................................................................28
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Contents
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 3

System Noise or Vibration...........................................................................................................................................................29
Sluggish System Response.........................................................................................................................................................29
Transmission Operates Normally in One Direction Only.................................................................................................30
Adjustments Standard Procedures.................................................................................................................................................................... 31
Charge Pressure Relief Valve Adjustments...........................................................................................................................31
Pressure Limiter Adjustment..................................................................................................................................................... 32
Engaging the Bypass Function..................................................................................................................................................34
Displacement Limiter Adjustment...........................................................................................................................................35
Control Neutral Adjustment.......................................................................................................................................................36
Mechanical Neutral Adjustment...............................................................................................................................................37
Minor Repair Standard Procedures, Removing the Pump.........................................................................................................................40
EDC Control......................................................................................................................................................................................40
Control Solenoids...........................................................................................................................................................................42
MDC Control.................................................................................................................................................................................... 42
Angle sensor on EDC.....................................................................................................................................................................45
Removal........................................................................................................................................................................................45
Installation...................................................................................................................................................................................46
EDC with angle sensor..................................................................................................................................................................46
Removal........................................................................................................................................................................................46
Installation...................................................................................................................................................................................47
Automotive Control......................................................................................................................................................................48
Bearing and Shaft Replacement...............................................................................................................................................52
External Filter Replacement.......................................................................................................................................................53
Filter Bypass Valve and Filter Bypass Switch........................................................................................................................54
Charge Pump...................................................................................................................................................................................55
High Pressure Relief Valves (HPRV)..........................................................................................................................................58
Charge Pressure Relief Valve......................................................................................................................................................59
Pressure Limiter Valve Replacement.......................................................................................................................................60
Torque Chart Fastener Size and Torques..........................................................................................................................................................62
Plug Size and Torques..................................................................................................................................................................62
Fasteners and Plugs...................................................................................................................................................................... 63
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Contents
4 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

Overview
This manual includes information on the installation, maintenance, and minor repair of H1 pumps. It
includes a description of the unit and its individual components, troubleshooting information, and minor
repair procedures.
Performing minor repairs requires the unit to be removed from the vehicle/machine. Thoroughly clean
the unit before beginning maintenance or repair activities. Since dirt and contamination are the greatest
enemies of any type of hydraulic equipment, follow cleanliness requirements strictly. This is especially
important when changing the system filter and when removing hoses or plumbing.
A worldwide network of Danfoss Authorized Service Centers is available for major repairs. Danfoss trains
and certifies Authorized Service Centers on a regular basis. You can locate your nearest Authorized
Service Center using the distributor locator at www.Danfoss.com.
Warranty
Performing adjustments and minor repairs according to the procedures in this manual will not affect your
warranty. Major repairs requiring the removal of a unit’s center section, servo sleeves, or front flange
voids the warranty unless a Danfoss Authorized Service Center performs them.
General instructions
Remove the unit
If necessary, remove the unit from the vehicle/machine. Chock the wheels on the vehicle or lock the
mechanism to inhibit movement. Be aware that hydraulic fluid may be under high pressure and/or hot.
Inspect the outside of the pump and fittings for damage. Cap hoses after removal to prevent
contamination.
Keep it clean
Cleanliness is a primary means of assuring satisfactory pump life on either new or repaired units.
Clean the outside of the pump thoroughly before disassembly. Take care to avoid contamination of the
system ports. Cleaning parts by using a clean solvent wash and air drying is usually adequate.
As with any precision equipment, you must keep all parts free of foreign material and chemicals. Protect
all exposed sealing surfaces and open cavities from damage and foreign material. If left unattended,
cover the pump with a protective layer of plastic.
Replace all O-rings and gaskets
Danfoss recommends that you replace all O-rings, seals and gaskets. Lightly lubricate all O-rings with
clean petroleum jelly prior to assembly.
Secure the unit
If removed from machine, place the unit in a stable position with the shaft pointing downward. It
will be necessary to secure the pump while removing and torquing fasteners and components.
Safety Precautions
Always consider safety precautions before beginning a service procedure. Protect yourself and others
from injury. Take the following general precautions whenever servicing a hydraulic system.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Introduction
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 5

Unintended machine movement
W
Warning
Unintended movement of the machine or mechanism may cause injury to the technician or bystanders.
To protect against unintended movement, secure the machine or
disable/disconnect the mechanism while servicing.
Flammable cleaning solvents
W
Warning
Some cleaning solvents are flammable. To avoid possible fire, do not use cleaning solvents in an area
where a source of ignition may be present.
Fluid under pressure
W
Warning
Escaping hydraulic fluid under pressure can have sufficient force to penetrate your skin causing serious
injury and/or infection. This fluid may also be hot enough to cause burns. Use caution when dealing with
hydraulic fluid under pressure. Relieve pressure in the system before removing hoses, fittings, gauges, or
components. Never use your hand or any other body part to check for leaks in a pressurized line. Seek
medical attention immediately if you are cut by hydraulic fluid.
Personal safety
W
Warning
Protect yourself from injury. Use proper safety equipment, including safety glasses, at all times.
Hazardous Material
W
Warning
Hydraulic fluid contains hazardous material. Avoid prolonged contact with hydraulic fluid. Always
dispose of used hydraulic fluid according to state, and federal environmental regulations.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Introduction
6 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

Symbols used in Danfoss literature
WARNING may result in injury Tip, helpful suggestion
CAUTION may result in damage to product or
property Lubricate with hydraulic fluid
Reusable part Apply grease / petroleum jelly
Non-reusable part, use a new part Apply locking compound
Non-removable item Inspect for wear or damage
Option - either part may exist Clean area or part
Superseded - parts are not interchangeable Be careful not to scratch or damage
Measurement required Note correct orientation
Flatness specification Mark orientation for reinstallation
Parallelism specification Torque specification
External hex head Press in - press fit
Internal hex head Pull out with tool – press fit
Torx head Cover splines with installation sleeve
O-ring boss port Pressure measurement/gauge location or
specification
The symbols above appear in the illustrations and text of this manual. They are intended to communicate
helpful information at the point where it is most useful to the reader. In most instances, the appearance
of the symbol itself denotes its meaning. The legend above defines each symbol and explains its purpose.
Design
Danfoss H1 closed circuit piston pumps convert input torque into hydraulic power. The input shaft
transmits rotational force to the cylinder block. Bearings at the front and rear of the pump support the
shaft. Splines connect the shaft to the cylinder block. A lip-seal at the front end of the pump prevents
leakage where the shaft exits the pump housing. The spinning cylinder block contains nine reciprocating
pistons. Each piston has a brass slipper connected at one end by a ball joint. The block spring, ball guide,
and slipper retainer hold the slippers to the swashplate. The reciprocating movement of the pistons
occurs as the slippers slide against the inclined swashplate during rotation. Via the valve plate, one half of
the cylinder block is connected to low pressure and the other half to high pressure. As each piston cycles
in and out of its bore, fluid is replenished by charge flow and displaced to the outlet thereby imparting
hydraulic power into the system. A small amount of fluid is allowed to flow from the cylinder block/valve
plate and slipper/swashplate interfaces for lubrication and cooling. Case drain ports return this fluid to
the reservoir.
The angle of the swashplate controls the volume and direction of fluid displaced into the system. The
servo piston controls the angle of the swashplate. The pump control, by varying the pressure at the servo
piston, controls the piston’s position. An electric signal to the control coils transmits the command from
the operator to the pump. Mechanical feedback of the swashplate position to the control through the
feedback pins allows for very precise displacement control and increases overall system stability. Non-
feedback control options do not use the mechanical feedback link.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Introduction
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 7

Cross section view
Swashplate Cylinder block
Auxiliary mounting pad “B”
Charge pump
Servo piston
Piston
Shaf t seal
Shaf t
Slippe r
Electric displacement control
P106 045E
Valve plate
Swashplate feedback pin
The System Circuit
The Basic Closed Circuit
Hydraulic lines connect the main ports of the pump to the main ports of the motor. Fluid flows in either
direction from the pump to the motor and back. Either of the hydraulic lines can be under high pressure.
In pumping mode the position of the pump swashplate determines which line is high pressure as well as
the direction of fluid flow.
Case Drain and Heat Exchanger
The pump and motor require case drain lines to remove hot fluid from the system. The pump and motor
drain from the topmost port to ensure the cases remain full of fluid. The motor case drain can connect to
the lower drain port on the pump housing or it can tee into the case drain line upstream of the heat
exchanger. A heat exchanger with bypass valve cools the case drain fluid before it returns to the
reservoir.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Introduction
8 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

System Circuit Diagram
P003 423E
Reservoir
Heat Exchanger Bypass Valve
Heat Exchanger
Electric Displacement Control
Servo Cylinder
Input Shaft
Pump Swashplate
Pressure Limiter Valve
Pressure Limiter
Valve
Charge Check/ High Pressure Relief Valve
Charge Check/ High Pressure Relief Valve
To Motor Case
Charge Pressure Relief Valve
Loop
Flushing
Valve
Charge Pressure Filter
Charge Pump
Output Shaft
Valve Segment
Bent Axis Variable Displacement Motor
Variable Displacement Pump
Case Drain
Working Loop A (Low Pressure) and Charge Pressure Servo
Pressure
Working Loop B (High Pressure) Suction
H1 Pump and H1 Motor with Electric proportional control
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Introduction
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 9

System Schematic
P003 424
min.max.
L2 NMA
A
B
M5 MB M4
L1
B
R1
R2
M4
M5
M14 M6 1 2
M3 L1 L2 MA
A
C2 C1
S
F00B F00A
L3 L4
CW
MB
max. 3 bar
[43.5 psi]
n
The schematic above shows the function of a hydrostatic transmission using an H1 axial variable
displacement pump with electric proportional displacement control (EDC) and an H1 bent axis variable
displacement motor with electric proportional control (L*) and integrated loop flushing device.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Introduction
10 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

Pressure Limiter Valves
Pressure limiter valves provide system pressure protection by compensating the pump swashplate
position when the set pressure of the valve is reached. A pressure limiter is a non-dissipative (non heat
generating) pressure regulating system.
Each side of the transmission loop (and each section of the tandem pump) has a dedicated pressure
limiter valve that is set independently. Each system port may have a different pressure limiter setting.
The pressure limiter setting is the maximum differential pressure between the high and low loops. When
the pressure limiter setting is reached, the valve ports oil to the lowpressure side of the servo piston. The
change in pressure across the servo rapidly reduces pump displacement. Fluid flow from the valve
continues until the resulting drop in pump displacement causes system pressure to fall below the
pressure limiter setting.
An active pressure limiter destrokes the pump to near neutral when the load is in a stalled condition. The
pump swashplate moves in either direction necessary to regulate the system pressure, including
increasing stroke when over-running or over-center.
The pressure limiter is optional on H1 pumps.
069/078/089/100 Single Pumps
115/130/147/165/210/250 Single Pumps
High Pressure Relief Valve (HPRV) and Charge Check
All H1 pumps have a combination high pressure relief and charge check valve. The high-pressure relief
function is a dissipative (heat generating) pressure control valve for the purpose of limiting excessive
system pressures. The charge check function replenishes the low-pressure side of the working loop with
charge oil. Each side of the transmission loop has a dedicated non-adjustable, factory-set HPRV valve.
When system pressure exceeds the factory setting of the valve, it passes oil from the high pressure
system loop into the charge gallery and the low pressure system loop via the charge check.
The pump may have different pressure settings at each system port. When an HPRV valve is used in
conjunction with a pressure limiter, the HPRV valve is always factory set above the setting of the pressure
limiter. The system pressure shown in the order code for pumps with only HPRV is the HPRV setting. The
system pressure shown in the order code for pumps with both pressure limiter and HPRV is the pressure
limiter setting.
HPRVs are set at low flow condition. Any application or operating condition which leads to elevated HPRV
flow will cause a pressure rise with flow above the valve setting. Consult factory for application.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operation
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 11

High Pressure Relief and Charge Check Valve with Bypass Valve in charging mode
P003 269
High Pressure Relief and Charge Check Valve with Bypass Valve in relief mode
P003 268
Pressures marked on HPRV valve
Mark Pressure bar [psi]
20 200 [2900]
25 250 [3626]
30 300 [4351]
35 350 [5076]
37 370 [5366]
40 400 [5801]
42 420 [6092]
45 450 [6527]
48 480 [6962]
51 510 [7397]
Bypass Function
The HPRV valve also provides a loop bypass function when each of the two HPRV hex plugs are
mechanically backed out 3 full turns. Engaging the bypass function hydraulically connects both A & B
sides of the working loop to the common charge gallery. The bypass function allows you to move a
machine or load without rotating the pump shaft or prime mover.
C
Caution
The HPRV valves are not tow valves. Damage to the pump and motor can occur when operating without
charge flow. Limit vehicle/machine movement to no more than 20% of maximum speed and no longer
that three minutes. Reseat the HPRV valves after vehicle/machine movement.
Charge Pressure Relief Valve
The charge pressure relief valve maintains charge pressure at a designated level above case pressure. The
charge pressure relief valve is a direct acting poppet valve that opens and discharges fluid to the pump
case when pressure exceeds a designated level. This level is nominally set with the pump running at 1800
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operation
12 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

min-1 (rpm). For external charge flow, the CPRV is set with with a flow of 30 l/min [8 US gal/min]. In
forward or reverse, charge pressure will be slightly lower than in neutral position. The model code of the
pump specifies the charge relief setting.
Typically charge pressure increases from 1.2-1.5 bar per 10 l/min [17.4-21.8 psi per 2.64 US gal/min] case
flow.
Charge Pressure Relief Valve
Electrical Displacement Control (EDC)
EDC Principle
The Electrical Displacement Control (EDC) consists of proportional solenoids on each side of a three-
position, four-way porting spool. The proportional solenoid applies a force to the spool, which ports
hydraulic fluid to either side of the servo piston. Differential pressure across the servo piston rotates the
swashplate, changing the pump‘s displacement from full displacement in one direction to full
displacement in the opposite direction.
EDC Operation
H1 EDC’s are current driven controls requiring a Pulse Width Modulated (PWM) signal. Pulse width
modulation allows more precise control of current to the solenoids. The PWM signal causes the solenoid
pin to push against the porting spool, which pressurizes one end of the servo piston, while draining the
other. Pressure differential across the servo piston moves the swashplate. A swashplate feedback link,
opposing control links, and a linear spring provide swashplate position force feedback to the solenoid.
The control system reaches equilibrium when the position of the swashplate spring feedback force
exactly balances the input command solenoid force from the operator. As hydraulic pressures in the
operating loop change with load, the control assembly and servo/swashplate system work constantly to
maintain the commanded position of the swashplate.
The EDC incorporates a positive neutral dead-band as a result of the control spool porting, spring preload
from the servo piston assembly, and the linear control spring. Once the neutral threshold current is
reached, the swashplate position becomes directly proportional to the control current. To minimize the
effect of the control neutral deadband, we recommended the transmission controller or operator input
device incorporate a jump up current.
The neutral position of the control spool does provide a positive preload pressure to each end of the
servo piston assembly.
When the control input signal is either lost or removed, or if there is a loss of charge pressure, the spring-
loaded servo piston automatically returns the pump to neutral position.
The EDC is a displacement (flow) control. Pump swashplate position is proportional to the input
command and therefore vehicle or load speed (excluding influence of efficiency), is dependent only on
the prime mover speed or motor displacement.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operation
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 13

EDC Schematic Diagram
Feedback from
Swash plate
PTF00B
M14
1C2C
F00A
P003 478E
Manual OverRide (MOR)
All controls are available with a Manual OverRide (MOR) for temporary actuation of the control to aid in
diagnosis. FNR controls always include MOR functionality.
W
Warning
Depressing the plunger causes the pump to go into stroke which will move the machine or mechanism.
Ensure the vehicle or machine is in a safe condition (wheels off the ground or mechanism disconnected)
before attempting to use the MOR feature.
An O-ring seals the MOR plunger. Initial actuation of the function requires additional force to overcome
the O-ring resistance. A threshold force of 45 N is typically required at first actuation. Additional
actuations typically require a threshold force of 12 N to move the MOR plunger. Force required to keep
the pump at full stroke is typically 51 N. Do not expect proportional control of the pump using the MOR.
Refer to control flow table for the relationship of solenoid to direction of flow.
Control Solenoid
P003 204
EDC Schematic Diagram Showing Manual OverRide
Feedback from
Swash plate
PTF00B
M14
C1
C2
F00A
P003 205E
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operation
14 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

Manual Displacement Control (MDC)
A Manual proportional Displacement Control (MDC) consists of a handle on top of a rotary input shaft.
The shaft provides an eccentric connection to a feedback link. This link is connected on its one end with a
porting spool. On its other end the link is connected the pumps swashplate.
This design provides a travel feedback without spring. When turning the shaft the spool moves thus
providing hydraulic pressure to either side of a double acting servo piston of the pump.
Differential pressure across the servo piston rotates the swash plate, changing the pump’s displacement.
Simultaneously the swashplate movement is fed back to the control spool providing proportionality
between shaft rotation on the control and swashplate rotation.
The MDC changes the pump displacement between no flow and full flow into opposite directions. Under
some circumstances, such as contamination, the control spool could stick and cause the pump to stay at
some displacement.
A serviceable 125 μm screen is located in the supply line immediately before the control porting spool.
The MDC is sealed by means of a static O-ring between the actuation system and the control block. Its
shaft is sealed by means of a special O-ring which is applied for low friction. The special O-ring is
protected from dust, water and aggressive liquids or gases by means of a special lip seal.
Manual Displacement Control
P301 749
Pump displacement vs. control lever rotation
"0" Lever rotation
"A"
Displacement
100 %
a
-a
100 %
"B"
-b
-d
bc
d
-c
P301 752
Legend:
Deadband on Bside – a= 3° ±1°
Maximum pump stroke – b= 30° +2/-1°
Required customer end stop – c= 36° ±3°
Internal end stop – d= 40°
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operation
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 15

MDC Torque
Description Value
Torque required to move handle to maximum displacement 1.4 N•m [12.39 lbf•in ]
Torque required to hold handle at given displacement 0.6 N•m [5.31 lbf•in]
Maximum allowable input torque 20 N•m [177 lbf•in]
C
Caution
Volumetric efficiencies of the system will have impacts on the start and end input commands.
MDC General Information
In difference to other controls the MDC provides a mechanical deadband. This is required to overcome
the tolerances in the mechanical actuation.
The MDC contains an internal end stop to prevent over travel. The restoring moment is appropriate for
turning the MDC input shaft back to neutral only. Any linkages or cables may prevent the MDC from
returning to neutral.
The MDC is designed for a maximum case pressure of 5 bar and a rated case pressure of 3 bar. If the case
pressure exceeds 5 bar there is a risk of an insufficient restoring moment. In addition a high case pressure
can cause the NSS to indicate that the control is not in neutral. High case pressure may cause excessive
wear.
Customers can apply their own handle design but they must care about a robust clamping connection
between their handle and the control shaft and avoid overload of the shaft.
Customers can connect two MDC’s on a tandem unit in such a way that the actuation force will be
transferred from the pilot control to the second control but the kinematic of the linkages must ensure
that either control shaft is protected from torque overload. To avoid an overload of the MDC, customers
must install any support to limit the setting range of the Bowden cable.
C
Caution
Using the internal spring force on the input shaft is not an appropriate way to return the customer
connection linkage to neutral.
General information - CCO
For the MDC with CCO option the brake port (X7) provides charge pressure when the coil is energized to
activate static function such as a brake release. The X7 port must not be used for any continuous oil
consumption.
Neutral Start Switch (NSS)
The Neutral Start Switch (NSS) contains an electrical switch that provides a signal of whether the control
is in neutral. The signal in neutral is Normally Closed (NC).
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operation
16 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

Neutral Start Switch schematic
P005 702
M14
M5 M4 M3
Neutral Start Switch data
Max. continuous current with switching 8.4 A
Max. continuous current without switching 20 A
Max. voltage 36 VDC
Electrical protection class IP67 / IP69K with mating connector
Case Gauge Port M14
The drain port should be used when the control is mounted on the unit’s bottom side to flush residual
contamination out of the control.
MDC schematic diagram
P005 701
M14
M5 M4 M3
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operation
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 17

Input speed
Minimum speed is the lowest input speed recommended during engine idle condition. Operating below
minimum speed limits the pump’s ability to maintain adequate flow for lubrication and power
transmission.
Rated speed is the highest input speed recommended at full power condition. Operating at or below
this speed should yield satisfactory product life.
Maximum speed is the highest operating speed permitted. Exceeding maximum speed reduces product
life and can cause loss of hydrostatic power and braking capacity. Never exceed the maximum speed
limit under any operating conditions.
Operating conditions between Rated and Maximum speed should be restricted to less than full power
and to limited periods of time. For most drive systems, maximum unit speed occurs during downhill
braking or negative power conditions.
For more information consult Pressure and speed limits, BLN-9884, when determining speed limits for a
particular application.
During hydraulic braking and downhill conditions, the prime mover must be capable of providing
sufficient braking torque in order to avoid pump over speed. This is especially important to consider for
turbocharged and Tier 4 engines.
W
Warning
Unintended vehicle or machine movement hazard
Exceeding maximum speed may cause a loss of hydrostatic drive line power and braking capacity. You
must provide a braking system, redundant to the hydrostatic transmission, sufficient to stop and hold the
vehicle or machine in the event of hydrostatic drive power loss. The braking system must also be
sufficient to hold the machine in place when full power is applied.
System pressure
System pressure is the differential pressure between high pressure system ports. It is the dominant
operating variable affecting hydraulic unit life. High system pressure, which results from high load,
reduces expected life. Hydraulic unit life depends on the speed and normal operating, or weighted
average, pressure that can only be determined from a duty cycle analysis.
Application pressure is the high pressure relief or pressure limiter setting normally defined within the
order code of the pump. This is the applied system pressure at which the driveline generates the
maximum calculated pull or torque in the application.
Maximum working pressure is the highest recommended application pressure. Maximum working
pressure is not intended to be a continuous pressure. Propel systems with application pressures at, or
below, this pressure should yield satisfactory unit life given proper component sizing.
Maximum pressure is the highest allowable application pressure under any circumstance. Application
pressures above Maximum Working Pressure will only be considered with duty cycle analysis and factory
approval.
Pressure spikes are normal and must be considered when reviewing Maximum Working pressure.
Minimum low loop pressure must be maintained under all operating conditions to avoid cavitation.
All pressure limits are differential pressures referenced to low loop (charge) pressure. Subtract low loop
pressure from gauge readings to compute the differential.
Servo pressure
Servo pressure is the pressure in the Servosystem needed to position and hold the pump on stroke. It
depends on system pressure and speed. At minimum servo pressure the pump will run at reduced stroke
depending on speed and pressure.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operating parameters
18 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308

Minimum servo pressure at corner power holds the pump on full stroke at max speed and max
pressure.
Maximum servo pressure is the highest pressure typically given by the charge pressure setting.
Charge pressure
An internal charge relief valve regulates charge pressure. Charge pressure supplies the control with
pressure to operate the swashplate and to maintain a minimum pressure in the low side of the
transmission loop.
The charge pressure setting listed in the order code is the set pressure of the charge relief valve with the
pump in neutral, operating at 1800 min-1 [rpm], and with a fluid viscosity of 32 mm²/s [150 SUS].
Pumps configured with no charge pump (external charge supply) are set with a charge flow of 30 l/min
[7.93 US gal/min] and a fluid viscosity of 32 mm²/s [150 SUS].
The charge pressure setting is referenced to case pressure. Charge pressure is the differential pressure
above case pressure.
Minimum charge pressure is the lowest pressure allowed to maintain a safe working condition in the
low side of the loop. Minimum control pressure requirements are a function of speed, pressure, and
swashplate angle, and may be higher than the minimum charge pressure shown in the Operating
parameters tables.
Maximum charge pressure is the highest charge pressure allowed by the charge relief adjustment, and
which provides normal component life. Elevated charge pressure can be used as a secondary means to
reduce the swashplate response time.
Charge pump inlet pressure
At normal operating temperature charge inlet pressure must not fall below rated charge inlet pressure
(vacuum). Minimum charge pump inlet pressure is only allowed at cold start conditions. In some
applications it is recommended to warm up the fluid (e.g. in the tank) before starting the engine and then
run the engine at limited speed. Maximum charge pump inlet pressure may be applied continuously.
Case pressure
Under normal operating conditions, the rated case pressure must not be exceeded. During cold start case
pressure must be kept below maximum intermittent case pressure. Size drain plumbing accordingly.
Auxiliary Pad Mounted Pumps. The auxiliary pad cavity of H1 pumps configured without integral charge
pumps is referenced to case pressure. Units with integral charge pumps have auxiliary mounting pad
cavities referenced to charge inlet (vacuum).
C
Caution
Possible component damage or leakage.
Operation with case pressure in excess of stated limits may damage seals, gaskets, and/or housings,
causing external leakage. Performance may also be affected since charge and system pressure are
additive to case pressure.
External shaft seal pressure
In certain applications, the input shaft seal may be exposed to external pressures. The shaft seal is
designed to withstand an external pressure up to 0.4 bar [5.8 psi] above the case pressure. The case
pressure limits must also be followed to ensure the shaft seal is not damaged.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operating parameters
©Danfoss | May 2018 520L0848 | AX00000087en-US0308 | 19

Temperature and viscosity
Temperature
The high temperature limits apply at the hottest point in the transmission, which is normally the motor
case drain. The system should generally be run at or below the quoted rated temperature.
The maximum intermittent temperature is based on material properties and should never be
exceeded.
Cold oil will generally not affect the durability of the transmission components, but it may affect the
ability of oil to flow and transmit power; therefore temperatures should remain 16 °C [30 °F] above the
pour point of the hydraulic fluid.
The minimum temperature relates to the physical properties of component materials.
Size heat exchangers to keep the fluid within these limits. Danfoss recommends testing to verify that
these temperature limits are not exceeded.
Viscosity
For maximum efficiency and bearing life, ensure the fluid viscosity remains in the recommended range.
The minimum viscosity should be encountered only during brief occasions of maximum ambient
temperature and severe duty cycle operation.
The maximum viscosity should be encountered only at cold start.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Operating parameters
20 | ©Danfoss | May 2018 520L0848 | AX00000087en-US0308