Lift Tek 35DV-MQ User manual

SERVICE MANUAL
35DV/45DV/55DV-MQ
Four Stage
Full FreeliŌMast
LTI # 263920 Lift Technologies, Inc.

Parts and Service
Tel : (864) 647 - 6320
Fax : (864) 647 - 7302
Toll Free : (877) 430 - 6302
Email : [email protected]
Lift Technologies, Inc.
7040 South Highway 11
Westminster, SC 29693
USA
Tel : (864) 647 - 1119
Fax : (864) 647 - 5406
Toll Free : (888) 946 - 3330
Website : www.lift-tek.com
LTI # 263920 Lift Technologies, Inc.

263920 R 2 Page 3
Page
4
4
4
5
5
5
6
7
7
7
8
8
Standard IHR 9
13
15
16
16
Cylinders 17
17
Free Lift Cylinder Description 18
19
20
Free Lift Cylinder Removal - Mast on Floor 21
Main Lift Cylinder Service 23
27
28
Valve 28
28
Carriage 29
Description 29
30
31
32
33
33
34
36
38
39
43
Chains 44
44
45
Main Lift Chain Adjustment 45
45
Chain Replacement 46
Free Lift Chain Adjustment
Channel Lubrication
Mast Skewing
Mast Inspection
Cylinder Operation
Free Lift Cylinder Service
Mast Removal
Main Lift Cylinders Description
PERIODIC MAINTENANCE, Section 3
TROUBLESHOOTING, Section 4
INTRODUCTION, Section 1
Introduction
Special Definitions
Mounting Bracket Installation
INSTALLATION INSTRUCTIONS, Section 2
Truck System Requirements
SERVICE, Section 5
Upright and Carriage Position, Chain Tension
Mast Installation
Chain Lubrication
Main Lift Cylinder Removal- Mast on Floor
Carriage Removal- Mast on Floor
Carriage Removal- Mast on Truck
Upright Disassembly
Piston Removal
Valve Cartridge Service
Carriage Inspection
Mast Uprights
Upright Description
Upright Operation
Measuring Chain Stretch
Upright Reassembly
Upright Inspection
Mast Skewing
Inspection and Tension
Contents

Page 4 263920 R 2
This manual provides the installation Instructions, periodic
maintenance requirements, troubleshooting and service
procedures for the Lift Tek Series Quad roller masts.
These masts provide excellent visibility for the lift truck
driver. The mast carriage and upright channels are all
roller-mounted which provides smooth operation and long
service life.
In any communication about the mast, refer to the mast
serial number stamped in the nameplate. If the nameplate
is missing, these numbers are also stamped on the
left-hand upper cheekplate. See Figure 1.
Special Definitions
WARNING
1.2
Introduction
A statement preceded by is information
that should be acted upon to prevent bodily injury. A
WARNING is always inside a ruled box.
CAUTION
A statement preceded by CAUTION is information that
should be acted upon to prevent machine damage.
IMPORTANT
A statement preceded by IMPORTANT that
possesses special significance.
NOTE
A statement preceded by NOTE is information that is handy
Tool Requirements
1.3
Listed below are the minimum tools needed to work on a.
METRIC
17, 19, 24 mm Open End or Socket Wrench
INCH
3/4, 13/16, 7/8, 15/16, 1.0, 1-1/16 in Open End or
Socket Wrench.
1/8 in. Allen Wrench
Snap Ring Pliers
Claw Type Spanner Wrench
Strap Wrench
Torque Wrench
2 lb. Dead Blow Hammer
Figure 1. Serial Mast Number Location
Introduction
1.1
WARNING
Left-Hand
Side of
Outer
Upright
MA3154.eps
45DV-MQ-001-00025-M
OR
Example:
55DV–MQ–001–00025–M
Stamped
Serial
Numbers
45DV-MQ-001-00025-M

263920 R 2 Page 5
Installation
2.1 Truck System
Requirements
To achieve maximum lifting capacity of the mast, the
truck relief valve should be set to relieve at the pressure
indicated in the chart below. This chart also indicates the
hose fitting size to use between the truck control valve
and masts valve.
* Valve inlet port is 3/4 in. SAE O-ring. See Figure 2.
WARNING: For proper truck stability or to
prevent interference, tilt restriction may be
required. Contact the truck manufacturer.
IMPORTANT: Lift Tek Masts are compatible with SAE 10W
petroleum base oil per Mil. Spec. MIL-0-5606 or MIL-0-2104
B only. Use of synthetic or aqueous base hydraulic oil is not
recommended. If fire resistant hydraulic oil must be used,
contact Lift Tek.
Relief
Pressure
Hose
Size
Fitting*
Size
2600 psi No. 8 min.
No. 8 min.
13/32 in. Orifice
FigFigure 2. Valve inlet Port.
MA0022.eps
Valve Inlet Port
3/4 in. SAE O-ring
2.2 Mounting Bracket
Installation
If it is necessary to install mounting brackets and cross-
members to fit your lift truck, consult with the nearest
Lift Tek Service Department listed on the back cover.
You must supply dimensions A through F shown in
Figure 3. Failure to install the correct brackets and cross-
members can result in mast structural failure, bodily injury
and loss of warranty.
Figure 3. Determining Mounting Bracket Location.
WARNING: Failure to install the correct
brackets and crossmembers can result in
mast structural failure, bodily injury and
loss of warranty.
E
F
A
B
C
D
Truck Cowl
Tilt Cylinders
Front View
Side View
MA0031.eps

Page 6 263920 R 2
2.3 Mast Installation
Installation
1. Raise and block the front end of the truck 1ft. (30 cm) per
ANSI B56.1 or drive the truck over a service pit.
2. Install the bearings to lower the axle mounts.
3. Lubricate the bearing surfaces of the lower axle and tilt
cylinder mounting brackets with chassis grease.
4. Lift the mast using an overhead hoist with chain hooks
attached to the upper outer crossmember. Position the mast
lower the axle mounts on the truck axle. Install the mount
caps and capscrews. Tighten the capscrews to the truck
manufacturer’s torque specifications.
IMPORTANT: Prior to connecting the tilt cylinders to the
mast, make sure the cylinders “bottom” evenly. Adjust the tilt
cylinders to prevent the mast from “racking” during tilting.
Refer to your truck service manual for procedures.
5. Connect the lift truck supply hose to the mast valve.
6. Connect the tilt cylinders to the mast anchor brackets.
Tighten the pin capscrews to the truck manufacturer’s
torque specifications.
NOTE: Use as few fittings as possible and always use 45o
fittings instead of 90o fittings. Keep the hose lengths to a
minimum. Avoid sharp bends or pinch points when routing
the hose.
7. Check the hydraulic fluid level in the truck hydraulic
tank when the Mast is fully lower. Fill if required.
MA0016.eps
5
6
23
4
4
FiFigure 4. Mast Installation.
Contact Lift Tek if
additional fittings are
required. See back
cover.

263920 R 2 Page 7
Installation
2.4 Mast Inspection
Check each of the following before using the Mast for the
first time.
CAUTION: The factory-set adjustments may not be
correct for your truck.
1. Inspect all chains for lubrication.
2. Inspect all chains for any visible damage.
3. Inspect the main lift chain adjustment for proper
tension and upright position.
4. Inspect the free lift chain adjustment for proper
tension and carriage position.
5. Inspect for lubrication in the Mast upright channels.
6. Check for Mast skewing.
MA2777.eps
Carriage 2 in.
Below Outer
Upright
Outer Upright
and Carriage
Flush Outer
Upright
*3 in.
Underclearance *5 in. Underclearance
NOTE: Underclearance is based on mast
production series, actual mast
underclearance may vary by truck
model.
Figure 5. Mast side view showing correct position
for uprights and carriage.
2.4-1 Chain Lubrication
The main and free lift chains have been factory lubricated
using heat and pressure to force the lubrication thoroughly
into the chain links. Avoid removal or contamination of
this factory-applied lubrication. Do not wash, sand blast,
etch, steam clean, or paint the chains for initial Mast
installation. If chains need lubrication, refer to
Section 5.6. Chain Service
2.4-2 Upright and Carriage
Position, Chain Tension
The main lift chains should be adjusted so that when the
unloaded Mast is fully lowered, the uprights are flush at
the bottom (see Figure 5). The free lift chains should be
adjusted so that when the unloaded Mast is fully lowered,
the carriage is properly positioned depending on the truck
type (see figure 6).
CONTINUED ON PAGE 8
MA0015.eps
Free Lift Chains
Adjusting Nuts
Outer Main
Lift Chain
Adjusting Nuts
Inner Main
Lift Chain
Adjusting
Nuts
Figure 6. Adjusting Chain Anchor
Location (driver’s view).

Page 8 263920 R 2
2.4-2 Upright and Carriage
Position, Chain Tension
( Continued )
Installation
All chains should also be adjusted for equal tension of the
pairs to ensure proper load distribution and mast opera-
tion. Chains are adjusted at the chain anchors (see
Figure 6 ). To determine equal tension, extend the
unloaded mast to put the chains under tension. Then press
the center of the strand with your thumb. Then press
at the same place on the other chain of the pair. Each
chain in a pair should have equal “give”.
If the uprights or carriage are not in correct adjust-
ment, of if the chain pairs do not have equal tension,
perform the Main Lift and Free Lift Chain Adjustments
as described in Section 5.6-3 and 5.6-4.
2.4-3 Channel Lubrication
MA0028.eps
Upright
Rails
Lubrication
Figure 7. Lubricating upright channels.
Inspect the upright channels for lubrication. If necessary,
lubricate the full length of each upright channel with
chassis lube or Kendall SR-12X (see Figure 7).
2.4-4 Mast Skewing
Extend the mast to full lift height and inspect for mast
skewing (see Figure 8).
* If the mast bends to the right at full extension, a shim(s)
needs to be removed from the left main lift cylinder rod.
* If the mast bends to the left at full extension, a shim(s)
needs to be installed on the left main lift cylinder rod.
To adjust the Mast to eliminate skewing, perform the Mast
Skewing Adjustment as described in Section 5.5-6.
MA0017.eps
Right Hand
Main Lift
Cylinder
Left Hand
Main Lift
Cylinder
Free Lift
Cylinder
Figure 8. Extending Mast to check for
skewing (driver’s view).
MA0020.eps
Snap
Ring
Shim
Outer
Intermediate
Upright
4 X 4 in.
( 10 X 10 cm)
Wood Block
Outer
Upright
Figure 9. Blocking upright to retract LH main lift cylinder rod..

263920 R 2 Page 9
Installation
2.4-2 Internal Reeving
STANDARD
1. Install the shaft, tires and hose guards to the
crosshead center plate (see Figure 10). Leave the
capscrew and nut finger-tight to allow for hose
installation.
2. Install the carriage hose bracket to the center tab
on the lower carriage bar.
3. Install the fittings to the bracket (see Figure 11).
* Single Function - Install the fittings to the
left or right side location. Tighten the
fittings finger-tight.
* Double Function - Install the fittings to the
left and right side location. Tighten the
fittings finger-tight.
4. Install the lower IHR bracket and plastic inserts to
the block at the bottom of the inner upright
weldment. Tighten capscrew to 52 ft-lbs (71Nm).
Do not install cover plate at this time.
5. Install the shaft and hardware to the inner interme-
diate upright chain sheave shaft. Tighten the
capscrew to 52 ft-lbs. (71 Nm). See figure 12.
MA3167.eps
1
Figure 10. Installing shaft, tires and hose guards on
crosshead.
MA3168.eps
3
2
Figure 11. Installing hose bracket and fittings on carriage.
MA0256.eps
3
SINGLE
FUNCTION
OR
DOUBLE
FUNCTION

Page 10 263920 R 2
Installation
MA3188.eps
Upper Hose Guide
16
19
17
19
Outer
Upright
Outer
Intermediate
Upright
Inner
Intermediate
Upright
Inner
Upright
Crosshead
Components
Carriage
Components
Lower Inner
Components
Lower Guides
7
9
5
6
4
Figure 12.Installing internal hose reeving components on uprights.
6. Install the lower hose guide to the outer intermedi-
ate upright. Tighten the capscrew to 30 ft-lbs (41
Nm).
7. Install hose clamps to lower guide. Leave
capscrews finger tight.
8. Completely lower the carriage. Route the short
hoses down behind the carriage bar to the carriage
bracket fittings. Connect the hose ends to the
fittings leaving the hose ends finger tight. 35DV
Double Function: The No. 4 hoses connect to the
two right fittings (viewed from the driver’s seat).
2.4-2 Internal Reeving
STANDARD ( Continued )
9. Route the hoses over the crosshead sheaves.
10. Route the hoses down between the freelift
cylinder and crossmember. Position the hoses in
their natural curve over the crosshead sheaves.
Tighten the hose ends at the carriage bracket.
11. Connect the long hoses to the short hoses behind
the freelift cylinder. The outside hose(s) is
approximately 4” shorter than the inside hose(s).
See figure 13.
12. Pull down on the hoses with approximately 30 lbs.
of force. Clamp the hoses to the lower bracket
attached to the inner upright crossmember.
Tighten the capscrews to a torque of 7-11 ft-lbs
(10-15 Nm).

263920 R 2 Page 11
Installation
2.4-2 Internal Reeving
STANDARD ( Continued )
Lower
Hose
Guide
Inner
Upright
Bracket
Inner
Intermediate
Upright Sheave
SINGLE
FUNCTION
DOUBLE
FUNCTION
MA3156.eps
8
15
8
SINGLE
FUNCTION
DOUBLE
FUNCTION
Carriage
Bracket
Fittings
15
20
16
18
SINGLE
FUNCTION
DOUBLE
FUNCTION
BACK VIEW
13
MA3157.eps
SINGLE
FUNCTION
DOUBLE
FUNCTION
BACK VIEW
13
MA3157.eps
Connect
hoses
11
Short
Hose
9
Long
Hose
Short
Hose
Long
Hose
Short
HosesLong
Hose
Long
Hose
13. Position the hoses with the tabs on the inner upright
bracket as shown in figure 13.
14. Install the lower IHR cover plate and hardware.
Tighten the capscrews to 30 ft-lbs (41 Nm).
15. Route the hoses up toward the top of the mast
following the inner lift chains. Bend the hoses over
the inner intermediate upright sheave and install the
sheave on the shaft bolted to the intermediate
upright. Install washer and retaining ring to shaft.
16. Route the hoses down to the lower hose guide.
Place hoses under the hose clamp at the top of
the lower hose guide. Pull downward on the hoses
with 20 lbs. of force. Tighten clamp capsrews
enough to stop hose movement.
17. Install the upper hose guide to the outer upright.
Tighten the capscrew to 30 ft-lbs. (41 Nm).
18. Loop the hoses approximately 5 in. (125mm)
below the bottom of the lower hose clamp and
rout upward into the upper hose guide.
Figure 13. Installing internal hose reeving on uprights.

Page 12 263920 R 2
Installation
2.4-2 Internal Reeving
STANDARD ( Continued )
Lower
Hose
Guide
Crosshead
MA3158.eps
25
19
24
22
Upper
Hose
Guide
19
23
24
21
19. Install the hose clamps to the upper hose guide.
Leave capscrews finger tight.
20. Route the hoses under the hose clamps at the top
of the upper hose guide. Tighten the capscrews
finger tight.
21. Route the hoses under the hose clamps at the
bottom of the upper hose guide. Do no tighten the
clamp capscrews.
22. Tighten the crosshead coverplate capscrew to a
torque of 52 ft.-lbs. (71 Nm).
23. Align the hoses by twisting the hose ends to
travel centered in the crosshead on the natural
curve of the hose. The hoses should travel
parallel to each other. Hold the hoses while
tightening the fittings to keep the hoses from
twisting.
24. Loosen the hose clamps at the top of the lower
hose guide. Pull down on the hoses with 40 lbs.
of force. Tighten the hose clamp capscrews to 7-
11 ft.-lbs. (10-15 Nm).
25. Loosen the hose clamps on the upper hose guide.
Adjust the hoses to the natural hose bend and
align evenly spaced in the guide rails. Tighten the
hose clamp capscrews to 7-11 ft.-lbs. (10-15
Nm).
26. Raise and lower the Mast slowly through several
cycles and check for proper hose alignment,
clearances and hose tracking in the guides.

263920 R 2 Page 13
Periodic Maintenance
3.1 Periodic Maintenance
For proper operation and an extended service lift, the quad
Mast should be inspected and serviced regularly as part of
your normal lift truck maintenance schedule according to
the following outlines and ANSI B56.1 procedures.
The recommended intervals are for Masts operating under
normal conditions. If operation is in severe conditions or
corrosive atmospheres, inspect the Mast more frequently,
WARNING: Never work on a raised mast with
a load without supports, or while anyone is near
the lift truck control handles per ANSI B56.1.
3.1-1 Daily Inspection
Perform the following at the beginning of each work shift:
1. Extend the carriage a few inches off the ground and
make sure the chains are under equal tension and that
the tops of intermediate-inner and inner weldments are
flush within 3mm of the intermediate-outer weldment.
Refer to Sections 5.6-3 and 5.6-4 for chain adjustment.
2. Extend the Mast to full height to make sure the uprights
and carriage extend freely without binding.
3. While the Mast is extended, inspect the upright rails for
lubrication. Refer to Section 5.5-5, Step 1 for lubrication.
4. Make sure the internal reeving hoses (if equipped) travel
evenly in the hose guides. Adjust the hose ends if re-
quired. Tighten loose fittings, avoid any hose twist.
3.1-2 100 - Hour Inspection
After each 100 hours of lift truck operation, and in addition to
the Daily inspection:
1. Inspect and lubricate the full length of the chains with
SAE 40 wt. oil or Bowman Heavy Load Red Grease.
CAUTION: The chains must be coated with a film of
lubricant at all times.
3.1-3 500 - Hour Inspection
After each 500 hours of lift truck operation, and in addition to
the Daily and 100 - Hour Inspections:
1. Measure load roller clearances in the carriage and Mast
uprights. Pry between the upright and load roller so that
the opposite load roller is tight against the upright (see
Figure 14 ). Total side-to-side clearance should be 1/16
in. (1.5 mm) max. across the tightest point throughout the
travel of the upright. If shimming is required, refer to
Section 5.4-2, Carriage Removal for carriage rollers, or
Section 5.5-3, Upright Disassembly.
MA0227.eps
.06 in.
(1.5 mm)
Max.
Pry Here Load
Rollers
.06 in.
(1.5 mm)
Max.
Thrust
Block
Thrust
Plugs
Figure 14. Measuring Load Roller and Thrust
Plug Clearances.

Page 14 263920 R 2
Periodic Maintenance
3.1-3 500 - Hour Inspection (Continued)
2. Measure thrust plug/block clearances in the Mast
uprights. Pry between the upright upper crossmembers
( see Figure 14 ). Clearance should be 1/16in. (1.5 mm)
max.. If thrust plug/block replacement is required, refer to
Section 5.5-3, Upright Disassembly.
3. Check the chains for wear and stretch. Refer to Section
5.6. Chains for complete chain service.
4. Check the backrest capscrews for tightness. Tighten
capscrews to 145 ft.-lbs. ( 195 Nm ).

263920 R 2 Page 15
Trouble Shooting
PROBLEM PROBABLE CAUSE SOLUTION
Empty a) Plugged inlet hose a) Unplug hose or replace.
b) Insufficient oil. b) Check the truck hydraulic system for
correct oil level in tank, defective pump or
pump drive, leaks in the lines or
disconnect control valve linkage. Repair
or replace as necessary.
c) Bent or jammed plunger. c) Repair or replace as necessary.
Loaded a) Plugged piston check valve. a) Unplug check valve or replace.
b) Truck relief valve setting low. b) Raise truck relief setting to specified level
c) Over capacity. c) Reduce load to specified capacity.
d) Mechanical bind due to bent plunger d) Remove mechanical bind by
or bad rollers. replacing/freeing plunger and rollers.
Cylinders drift- a) External leak in pressure line. a) Tighten or replace as necessary.
b) Truck valve defective-cycle to full b) Repair or replace truck valve.
lift height to verify.
c) External leaks at retainer. c) Replace all cylinder seals.
d) Piston check valve leaking. d) Replace check valve.
Spongy or jerky action- a) Sticky or defective truck relief valve. a) remove and check the truck relief valve. If
contaminated oil caused the malfunction,
drain and flush the system, change the
filter and refill with fresh oil.
b) Bent or damaged cylinder plunger. b) Disassemble, check and repair cylinder
assembly.
c) Load rollers not properly adjusted c) Adjust or repair as necessary.
or defective.
d) Mast channels improperly lubricated. d) Lubricate mast.
e) Low Battery charge. e) Charge battery.
f) Low pump volume. f) Install accumulator.
g) Low oil level. g) Fill oil reservoir.
h) Insufficient hydraulic tank capacity h) Install larger tank baffles
or baffles.
Other. Contact Lift Technologies
WARNING: Extreme care should be used when working on a unit
when the carriage (with or without a load) is in the raised position.
WARNING: Extreme care should be used when working on a unit
when the carriage (with or without a load) is in the raised position.
WARNING: Extreme care should be used when working on a unit
when the carriage (with or without a load) is in the raised position.
Cylinders don’t lift load or
won't move
WARNING: Extreme care should be used when working on a unit
when the carriage (with or without a load) is in the raised position.
WARNING: Extreme care should be used when working on a unit
when the carriage (with or without a load) is in the raised position.
WARNING: Extreme care should be used when working on a unit
when the carriage (with or without a load) is in the raised position.
The Following Table lists problems that may be encountered on your Quad Mast, the probable causes, and the
recommended corrective action that should be taken to restore the Mast to normal operating condition.
4.1 Troubleshooting Chart

Page 16 263920 R 2
Service
1. Raise and block the front end of the truck up 1 ft. ( 30
cm ) or drive the truck over a service pit.
2. Disconnect the lift truck supply hose from the Mast
valve. Plug the hose end and cap the valve fitting.
3. Attach overhead hoist chains to the outer upright
crossmember. Take up slack in the chains.
4. Disconnect the tilt cylinders from the mast anchor
brackets, For reassembly, tighten the pin capscrews to
the truck manufacture’s torque specifications.
5. Disconnect the Mast lower mounts. For reassembly,
tighten the capscrews to the truck manufacture’s
torque specifications.
6. Lift the Mast away from the truck.
7. To install the mast, refer to Section 2.2, Mast Installation.
WARNING: Do not stand on or near the Mast
while it is suspended by an overhead hoist.
WARNING: Do not stand the Mast up vertically
unless it is chained to a support.
5
MA0228.eps
4
3
2
Figure 15. Removing Mast from Truck.
5.1 Mast Removal

263920 R 2 Page 17
Service
5.2 Cylinders
5.2-1 Main Lift Cylinder
Description
Left Hand Main Lift Cylinder Right Hand Main Lift Cylinder
Figure 16a. Main Lift Cylinders.
The main lift cylinders (see Figure
16) are single stage displacement
type cylinders consisting of a shell
and a telescoping plunger/piston
assembly. During extension
hydraulic pressure is acting
against the plunger outer diameter
due to the internal porting through
the piston. The piston seals do not
affect cylinder extension. The
truck hoist control valve holds the
cylinders in place once extension
has stopped.
The shell is internally threaded at
the top end to hold the retainer.
The retainer seals provide a high-
pressure hydraulic seal against
the plunger. The retainer also
limits the upward stroke of the
plunger.
A piston is attached to the bottom
end of the plunger. The piston
seal provides a high-pressure
hydraulic seal against the shell
that engages the cushion valve
when the cylinder is fully lowered.
A hydraulic fuse/cushion valve is
located in the LH cylinder’s inlet
port. In case of a hose failure
between the lowering control valve
and the cylinders, the fuse limits
the lowering speed of the
cylinder.
TYPICAL ILLUSTRATION
Torque to 100 ft-lbs MIN
Install with LOCTITE 242
Torque to 50 ft-lbs MIN.
Piston
Hydraulic
Tube
Retainer
O-Ring
Fitting
Fitting
Spacer
(If required)
Piston Seal
Plug
Wear Ring
Retaining Ring
Rod Seal
Wiper
Rod End
Shell
Rod
Install with
Loctite 242
Torque to:
50 ft-lbs MIN.
MA2178.eps
External Fuse
O-Ring

Page 18 263920 R 2
Service
5.2-2 Free Lift Cylinder
Description
The free lift cylinder (see Figure 17) is a single stage piston
type cylinder consisting of a shell and plunger/piston
assembly. During extension hydraulic pressure is acting
against the fill piston area. The truck hoist control valve
holds the cylinder in place once extension has stopped.
The shell is internally threaded at the top end to hold the
retainer. The retainer seals provide a high-pressure
hydraulic seal against the plunger. The retainer also limits
the upward stroke of the plunger.
A piston is attached to the bottom end of the plunger. The
piston seal provides a high-pressure seal against
the shell. A check valve located in the bottom of the piston
allows residual oil between the shell and plunger to escape
when the cylinder is extending (except for figure 17c).
A hydraulic fuse/cushion valve is located in the cylinder
inlet port. In case of hose failure between the lowering
control valve and the cylinder, the fuse limits the lowering
speed of the cylinder.
MA3169.eps
Part Number
Stamped Here
Check Valve
Install O-ring onto vlave
before assembly - valve
orientaion critical
O-Ring
Install with
Loctite 242
Plug
Wear Ring
Piston Seal
Piston
Retaining Ring
Rod
Hydraulic Tube
Install with
Loctite 242
Shell
O-Ring
Back-Up Ring
O-Ring
Retainer
Rod Seal
Wiper
Add 80ml +/- 15 ml of oil
to this area before installing
retainer.
Snap Ring
Fitting
Figure 17a. Free Lift Cylinder.
TYPICAL ILLUSTRATION

263920 R 2 Page 19
Shell
Inlet Port
To Truck Valve
Free Lift Cylinder
Plunger
Piston
Hydraulic Fuse/
Cushion Valve
Left Hand Main
Lift Cylinder
Right Hand Main
Lift Cylinder
Lowering
Control Valve
Quad Mast (MQ) Hydraulic Schematic
Plunger
Piston
Shell
Figure 18. Quad Mast Hydraulic Schematic.
Service
5.2-3 Cylinder Operation
1. Actuating the truck hoist control valve to raise
causes hydraulic fluid to enter the lowering
control valve through the inlet port where it
flows unrestricted through the lowering
control cartridge.
2. Hydraulic fluid flows to the cylinder inlet ports.
Due to the larger bore diameter of the free
lift cylinder compared to both main lift
cylinders, the free lift cylinders raise first.
3. Hydraulic fluid flows through the free lift cylinder
hydraulic fuse/cushion valve to the bottom of the
piston. Lifting force is created against the bottom
of the piston causing the plunger to raise.
Hydraulic fluid in the areas between the plunger
and the shell is allowed to escape through the
Check valve in the piston as the plunger raises
to the end of its stroke.
4. Hydraulic fluid flows through the hydraulic fuse/
cushion valve to the bottom of the pistons as the
free lift cylinder has fully extended, lifting force is
created against the bottom of the main lift cylinder
pistons causing their plungers to raise. Hydraulic
fluid in the area between the plunger and the shell
is allowed to escape through the check valve in
the piston as the plunger raises.
5. When hydraulic fluid flow from the truck hoist control
valve is discontinued, the cylinders are held in
position by the closed center spool of the truck valve.
Cylinder Raising
Cylinder Lowering
1. Actuating the truck hoist control valve to lower the
mast causes the main lift cylinder plungers then free lift
cylinder plunger to lower, forcing hydraulic fluid out
through the hydraulic fuse/cushion valves.
Note: The restriction setting of each hydraulic fuse is
lower (allows more flow) than the setting of the
lowering control valve. The hydraulic fuses restrict flow
only during failure of a lowering control valve or hose.
2. Hydraulic fluid flows to the lowering control valve
where it is restricted at a controlled speed determined
by the load being handled.
3. As the main lift cylinder pistons lower over the spear in
the bottom of the shell, a high pressure area is
developed between the piston and the shell which
engages the cushion valva to restrict flow. This allows
the plunger/piston just prior to bottoming, providing a
smooth transition to free lift cylinder lowering.

Page 20 263920 R 2
Service
5.2-4 Main Lift Cylinder Removal - Mast on Floor
1. Remove the mast from the truck as described in
Section 5.1.
2. Insert a 2 X 4 in. ( 5 X 10 cm ) wood block between the
lower crossmembers of the outer upright and outer
intermediate upright to prevent uprights from moving
out the bottom of the Mast.
3. Lay the Mast face-down on wood blocks (Figure 19).
Block under each end of the outer upright so the Mast
is level, and the inner uprights and carriage are free to
move.
4. Using a 1-in. wrench, disconnect the cylinder supply
hoses from the cylinder inlet ports. Using a 1-in.
socket, remove the special long fittings from the
cylinder ports and install plugs.
5. Remove the snap ring from the top of the LH cylinder
rod, and the tube and fitting from the top of the RH
cylinder rod. Plug the cylinder port.
6. Roll the uprights through the top of the Mast 1 - 2 ft.
( 30-60 cm), disengage the cylinder rods from the
outer intermediate upright.
7. Lift the cylinder from its base mounting boss in the
outer upright and angle inward. Remove the cylinders
through the sides of the uprights.
8. Note the number of shims (if equipped) on each
cylinder rod.
9. For reassembly, reverse the above procedures.
Figure 19. Removing Main Lift Cylinders.
MA0232.eps
3
2
8
5
4
8
5
7
7
6
Snap
Ring
Shim
MA0233.eps