Eaton 26 Series Owner's manual

December,1995
Eaton®
Gear Pumps
Repair Information
Series 26
Model 26000 Multiple Gear Pumps

2
Series 26 - Model 26000 Multiple Gear Pump
Introduction
Table of Contents
Introduction ................................................................................................................................ 2
Identification............................................................................................................................... 3
Tools Required ........................................................................................................................... 3
Exploded View Drawing .............................................................................................................. 4
Parts List .................................................................................................................................... 5
Disassembly ............................................................................................................................... 5 & 8
Reversibility ................................................................................................................................ 9
Inspection................................................................................................................................... 10
Reassembly ................................................................................................................................11 & 14
Specific Backplate Parts List....................................................................................................... 15
Placing Pump Back into Operation ............................................................................................. 16
Trouble Shooting ........................................................................................................................ 17
Ordering Information .................................................................................................................. 20
Introduction
This manual provides service information for the Eaton model 26000 multiple gear pumps. Step by step
instructions for the complete disassembly, inspection, and reassembly of the pumps are included.
The following recommendations should be followed to insure successful repairs.
Remove the pump from the application.
Cleanliness is extremely important.
Clean the port areas thoroughly before disconnecting the hydraulic lines.
Plug the pump ports and cover the open hydraulic lines immediately after they're disconnected.
Drain the oil and clean the exterior of the pump before making repairs.
Wash all metal parts in clean solvent.
Use compressed air to dry the parts. Do not wipe them dry with paper towels or cloth.
The compressed air should be filtered and moisture free.
Always use new seals when reassembling hydraulic pumps.
For replacement parts and ordering information refer to parts list 6-635.
Lubricate the new rubber seals with a petroleum jelly (vaseline) before installation.
Torque all bolts over gasket joints, then repeat the torquing sequence to makeup for gasket
compression.
Verifying the accuracy of pump repairs on an authorized test stand is essential.

3
Series 26 - Model 26000 Multiple Gear Pump
Identification and
Tools Required
B 95 01 31 JB Serial Number Code:
Series
26 = Gear Pump
( SAE "A" Mount )
Features
0 = Standard Single Pump
1= Standard Single W/ Relief
2= Flow Divider Backplate
3= Flow Divider W/ Load Sense
4= Tandem Backplate
5= Multiple Pumps
Displacement cm3/r [ in3/r]
01 = 6.6 [.40] 08 = 22.5 [1.37]
02 = 8.2 [.50] 09 = 24.3 [1.48]
03 = 9.5 [.58] 10 = 25.2 [1.54]
04 = 10.8 [.66] 11 = 27.7 [1.69]
05 = 13.8 [.84] 12 = 29.0 [1.77]
06 = 16.7 [1.02] 13 = 30.6 [1.87]
07 = 19.7 [1.20]
Input Rotation
R= Right-hand (clockwise)
L= Left-hand (Counterclockwise)
Catalog / Non-Catalog
Z= Cataloged Pump
A-Y = Non-Cataloged Pump
Shafts , Porting Size and Location
Side Ports
A= 3/4 in. 11 Tooth, 1 5/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
C= 3/4 in. Str. Keyed, 1 5/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
E= 3/4 in. 9 Tooth, 1 5/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
G= 5/8 in. Str. Keyed, 1 1/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
J= 5/8 in. 9 Tooth, 1 1/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
L= 5/8 in. Str. Keyed, 1 5/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
N= 3/4 in. 11 Tooth, 1 1/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
R= 3/4 in. Str. Keyed, 1 1/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
Rear Ports
B= 3/4 in. 11 Tooth, 1 5/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
D= 3/4 in. Str. Keyed, 1 5/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
F= 3/4 in. 9 Tooth, 1 5/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
H= 5/8 in. Str. Keyed, 1 1/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
K= 5/8 in. 9 Tooth, 1 1/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
M= 5/8 in. Str. Keyed, 1 5/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
P= 3/4 in. 11 Tooth, 1 1/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
S= 3/4 in. Str. Keyed, 1 1/16-12 UN-2B Suction, 7/8-14 UNF-2B Pressure
Product Number: 26 5 01 - R Z A
Tools Required
3/8 in. socket and ratchet wrench
Internal Retaining Ring Pliers
(straight .090 tip)
O-ring Pick
Thread 3/8 dia. UNC bolt/screw
Torque Wrench
(135.6 N.m [100 lbf.ft] capacity)
Hammer (soft face)
Light Petroleum Jelly
Seal Driver
Arbor Press
Testers Initials
Day of Month (two digits)
Month (two digits)
Last two digits of year built.
( 95 for 1995 etc.)
Revision level of parts list.

4
Series 26 - Model 26000 Multiple Gear Pump
Parts
Drawing
Shown below
Righthand (CW) Rotation
Triple Pump
8
Backup Gasket
9
Wear Plate
10
Seal
14
O-ring
57
Plug
10
Seal
10
Seal
9
Wear Plate
9
Wear Plate
8
Backup Gasket
8
Backup
Gasket
14
O-ring
14
O-ring
48
Adapter-Rear
15
Adapter-Front
7
Idler Gear
Assembly-Rear
29
Idler Gear
Assembly-Center
6
Idler Gear
Assembly-Front
14
O-ring
14
O-ring
14
O-ring
28
Body
3
Body
4
Body
Rear
45
Key
49
Gear-Center
26
Key
44
Gear-Rear
5
Drive Gear
Assembly
1
Front Plate
50
Washer
13
Cap Screws
11
Shaft seal
12
Washer
2
Backplate
25
Key
53
Plug
53A
O-ring
54
(Optional)
First Pump
Second Pump
Third Pump
Parts not
included in
double pump

5
Series 26 - Model 26000 Multiple Gear Pump
Disassembly
Repair Information - Model 26000
Work in a clean area; cleanliness is extremely important when
repairing hydraulic pumps. Before disconnecting the lines,
clean port areas of pump. Disconnect hydraulic lines, removing
pump assembly from vehicle and plugging ports. Thoroughly
clean the outside of the pump. After cleaning, remove port
plugs and drain oil.
Disassembly of a Triple Pump
During disassembly keep all mating part in order and together.
1 Remove key from drive shaft if keyed drive gear assembly
is used.
2 Put a location mark across front plate, bodies, adapters
and backplate to assure proper reassembly.
3 Clamp pump in vise, shaft end up.Caution must be used as
excessive clamping pressure on pump housing may distort the
housing.
4 Remove cap screws (eight each) and washer (four each).
5 Remove pump from vise and position pump so that the
shaft end is down. Now disassembly will continue from the
rear of the pump.
6 Start by tapping the backplate with a soft faced hammer
to remove from the third pump body. Remove o-ring seal from
backplate.
7 To disassemble the relief valve backplate and flow divider
backplate see page 15.
Parts List
Item
No. Description Qty.
1 Frontplate Assembly 1
2 Backplate 1
3 Body Assembly – Front 1
4 Body Assembly – Rear 1
5 Drive Gear Assembly 1
6 Idler Gear Assembly – Front 1
7 Idler Gear Assembly – Rear 1
~ 8 Backup Gasket A/R
~ 9 Wear Plate A/R
~ 10 Seal A/R
~ 11 Shaft Seal 1
~ 12 Washer 1
13 Cap Screw 8
~ 14 O-ring A/R
15 Adaptor Plate– Front 1
25 Key for Straight Shaft 1
26 Key – Rear Gear 1
28 Body Assembly – Center A/R
29 Idler Gear Assembly – Center A/R
44 Gear – Rear 1
45 Key – Center Gear A/R
48 Adaptor Plate – Rear 1
49 Gear – Center A/R
50 Washer 4
53 Plug Assembly 1
~ 53A O-ring 1
~ 57 Plug 1
~ 26000-902 Seal Kit for Double Pump
~ 26000-903 Seal Kit for Triple Pump
A/R – As Required
~ – Parts contained in seal kits

6
Series 26 - Model 26000 Multiple Gear Pump
Disassembly
8 To separate the third pump body from adapter plate use a
soft faced hammer and tap to loosen and then lift straight up.
9 Remove idler gear assembly from wear plate and adaptor
plate.
10 Remove drive gear from input shaft.
11 Remove wear plate and o-ring seal , noting position of
open or closed side of wear plate.
12 Using a pencil magnet remove the drive gear key from the
drive shaft.
13 Using a o-ring pick or similar tool and remove the o-ring
seal from the rear adapter plate.
14 Tap rear adapter plate with a soft faced hammer to loosen
and remove adapter plate. After removing adapter, turn it over
and remove the second o-ring seal .

7
Series 26 - Model 26000 Multiple Gear Pump
20 Tap front adapter plate with a soft faced hammer to loosen
and remove adapter plate. After removing adapter, turn it over
and remove the second o-ring seal .
21 Remove first pump body from front plate.
22 Remove first pump idler gear and input drive gear
assembly along with wear plate and o-ring seal from front
plate.
15 Remove second or middle pump body from second set of
gears.
16 Remove idler gear assembly from wear plate and drive
gear from input shaft.
17 Remove the next (second) wear plate assembly from the
adapter.
18 Next, use a pencil magnet to remove the second drive key
from the pump shaft.
19 Remove the o-ring seal from the front adapter plate.

8
Series 26 - Model 26000 Multiple Gear Pump
23 Remove back-up gasket a nd seal from all wear plates.
24 Using a drift punch or similar tool, remove the shaft seal
from the front plate. Caution is needed not to damage counter
bore of shaft seal area when removing seal.
25 Removing the plug in front plate is not necessary, unless
you intend to change rotation. See Reversibility - Changing
Input Rotation of Pump.

9
Series 26 - Model 26000 Multiple Gear Pump
Reversibility
Changing Input Rotation of Pump
1 To change input rotation of a double or triple pump a
complete disassembly is required.
2 Follow the steps below to alter the front plate assembly to
the desired rotation required.
- Thread 3/8 UNC threaded bolt into plug cavity. Start
with fingers, then place bolt head in vise and turn front
plate to engage threads 2-3 turns.
- Holding bolt in vise, tap front plate with rubber
hammer to disengage plug .
- Remove plug from bolt.
- Install plug in the other casting cavity and tap flush
with rubber hammer. Note L or R at bottom of cavity.
57
Plug
57
Plug
Open for
righthand
rotation
Open for
lefthand
rotation
R
L
R
L
- Ensure that bearing drain holes are free of debris.
3 After changing plug into proper cavity start the reassembly
portion of this booklet.

10
Series 26 - Model 26000 Multiple Gear Pump
Minimum Gear Width per Displacement
Model Number 26001 26002 26003 26004 26005 26006 26007 26008 26009 26010 26011 26012 26013
Pump Disp. 6,6 8,2 9,5 10,8 13,8 16,7 19,7 22,5 24,3 25,2 27,7 29,0 30,6
cm3/r [in3/r] [.40] [.50] [.58] [.66] [.84] [1.02] [1.20] [1.37] [1.48] [1.54] [1.69] [1.77] [1.87]
Gear Width 7,85 9,75 11,20 12,95 16,15 19,35 22,56 25,76 28,12 28,96 32,16 33,78 35,36
mm [in] [.309] [.384] [.441] [.510] [.636] [.762] [.888] [1.014] [1.107] [1.140] [1.266] [1.330] [1.392]
Inspection
Front plate and Backplate Inspection
1Oil groove in bushings in front plate should be in line with
dowel pin holes and 180°apart. The oil grooves in the
backplate bushings should be at approximately 37°to the
pressure side.
2Replace the backplate, adapter plate or front plate if I.D. of
bushings exceed 19,2 mm [.755 in] (Bushings are not available
as separate items).
3Bushings in front plate should be at 3,20 mm [.126 in]
above surface of front plate.
4Bushings in adapter plate on the wear plate side should be
at 3,20 mm [.126 in] above surface of adapter.
5Check for scoring on face of backplate orbackplate side of
adapter plate. Replace if wear exceeds ,038 mm [.0015 in.].
Body Inspection
1Check body inside gear pockets for excessive scoring or
wear.
2 Replace body if I.D. of gear pockets exceeds 43,7 mm
[1.719 in].
Inspect Parts for Wear
General
1 Clean and dry all parts.
2 Remove all nicks and burrs from all parts with emery
cloth.
Gear Assembly Inspection
1 Check spline drive shaft for twisted or broken teeth or
check keyed drive shaft for broken or chipped keyway.
2Inspect both the drive gear and idler gear shafts at
bushing points and seal area for rough surfaces and excessive
wear.
3Replace gear assembly if shaft measures less than 19 mm
[ .748 in] in bushing area. (One gear assembly may be replaced
separately; shafts and gears are available as assemblies only.)
4Inspect gear for scoring and excessive wear.
5Replace gear assembly if gear width is below the following
dimensions. Refer to chart on this page.
6Assure that snap rings are in grooves on either side of
drive and idler gears.
7If edge of gear teeth are sharp, break edge with emery
cloth or stone.

11
Series 26 - Model 26000 Multiple Gear Pump
4 Install new seal and new backup gasket into all wear plates.
Note in the middle of the backup gasket a flat section or
support. This area must face away from the wear plate inside
the seal.
5 Place the first new wear plate, seal, and backup gasket into
gear pocket with seal and backup gasket next to front plate. The
side of the wear plate with the mid section cut-away must be on
the suction side of pump.
6 Dip gear assemblies into oil and slip first shaft assemblies
into front plate bushings and gears into body pockets.
Reassembly
General Information
It is important that the relationship of the backplate, bodies,
adapters, wear plates, and front plate is correct. You will note
two half moon cavities in the body. The smaller half moon port
cavity must be on the pressure side of the pump. The side of
wear plate with midsection cut out must be on suction side of
pump. Suction side of backplate or adapter is always side with
larger port boss.
Reassembly
1 During the reassembly, replace and lubricate all of the wear
plates, seals, back-up gaskets, shaft seal and o-rings as new
parts. Lubricate all finished parts and/or assembly surfaces
freely with clean hydraulic fluid during assembly.
2 Install o-ring in groove of front plate.
3 Apply a thin coat of petroleum jelly or hydraulic oil to both
milled gear pockets of body. Slip body onto front plate with half
moon port cavities in body facing away from front plate. Check
and align the previously scribed line on the exterior of pump
unless input rotation was changed.
Note: If rotation was changed, make sure the small half moon
port cavity is on the pressure side (the plugged side of the front
plate) of the pump.

12
Series 26 - Model 26000 Multiple Gear Pump
Reassembly
7 Install new o-ring in groove of adapter plate (side with
bushings below surface).
8 Align the scribed lines of the first body and front adapter,
install adapter plate onto the drive shaft and body.
9 Lubricate and install second o-ring onto adapter.
10 Install the drive key into the key slot using some petroleum
jelly to help hold it in place.
11 Aligning the previously scribed line of body and adapter,
install the second pump body onto the adapter plate.
12 Lubricate and install the second wear plate assembly into
the pump body. Caution is required to not dislodge the seals
during installation. Remember sealing side of the wear plate is
toward the adapter plate with the cut side of the wear plate
facing the suction side or large cavity location of pump body.
13 Lubricate and install the second drive gear onto the shaft
and into the pump body aligning key with slot in gear.
14 Lubricate and install the second idler gear assembly into
body and adapter.

13
Series 26 - Model 26000 Multiple Gear Pump
15 Lubricate and install the new o-ring seal onto the rear
adapter plate.
16 Aligning the two previously scribed lines on the body and
rear adapter, install rear adapter onto pump body. Lubricate and
install the new o-ring seal onto the other side of rear adapter
plate.
17 Install the third drive key into the key slot using petroleum
jelly to help hold it in place.
18 Aligning the previously scribed line of body and adapter,
install the third pump body onto the rear adapter plate.
19 Lubricate and install the third wear plate assembly into the
pump body. Caution is required to not dislodge the seals
during installation. Remember sealing side of the wear plate is
toward the adapter plate with the cut side of the wear plate
facing the suction side or large cavity location of pump body.
20 Lubricate and install the third drive gear onto the shaft and
into the pump body aligning key with slot in gear.
21 Lubricate and install the third idler gear assembly into body
and adapter.
22 Install the new o-ring seal in groove of backplate.
23 Check scribe line, make sure port orientation is correct and
then slide backplate over gear shafts until dowel pins are
engaged.
24 Secure with cap screws and new washers . Tighten cap
screws evenly in a crisscross pattern 34 to 38 N•m [25 to 28
lbf•ft] torque.

14
Series 26 - Model 26000 Multiple Gear Pump
25 Place washer over drive shaft into housing. Liberally oil
shaft seal and install over drive shaft, carefully so that rubber
sealing lips are not cut.
26 Place 1-5/16 in. O.D. sleeve over shaft and press in shaft
seal until its below the surface of the front plate 6.1mm [.24
in].Install retaining ring if required optional feature is used.
27 Install key on keyed shaft.
Note: Refer to Start-up Procedure and Trouble Shooting
Procedure.

15
Series 26 - Model 26000 Multiple Gear Pump
Specific Backplate Parts List
Item
No. Description Qty.
2 Relief Valve Backplate 1
18 O-ring 3
19A Relief Valve Assembly 1
19A1 Relief Valve 1
~ 19A2 O-ring 1
~ 19A3 Backup Ring 1
~ 19A4 O-ring 1
19B Plug Assembly 1
19B1 Plug 1
Item
No. Description Qty.
2C Flow Divider Backplate 1
19A Relief Valve Assembly 1
19A1 Relief Valve 1
~ 19A2 O-ring 1
~ 19A3 Backup Ring 1
~ 19A4 O-ring 1
19B Plug Assembly 1
19B1 Plug 1
20 Flow Divider Spool 1
21 Plug/O-ring Assembly 1
21A Plug 1
~ 21B O-ring 2
22 Plug/O-ring Assembly 1
22A Plug 1
23 Spring 1
24 Shim (.0239 inch thick) A/R
A/R – As Required
3 Remove flow divider plugs, shims, spring, and spool from
backplate. (Notice orientation of spool with cavity in backplate)
4 Install new plug seals on plugs. Install spool, spring,
shims, and plug assemblies into backplate. Torque plugs 29 to
33 N•m [21 to 24 lbf•ft]
21B
22A
22
2C
20
23
24
19A4
21A
21
19A319A2
19B1
19B
21B
19A4
19A2
19A3
19A1
19A
Flow Divider Backplate
Disasembly and Reassembly
1 After removing relief valve or plug , remove and replace o-
ring and backup ring with new parts.
2 Install relief valve or plug and torque 41 to 46 N•m [30 to
34 lbf•ft]
19A4
19A2
19A3
19A1
19A
2B
Relief Valve Backplate
Disasembly and Reassembly
1 After removing relief valve , remove and replace o-rings
and backup ring with new parts.
2 Install relief valve and torque 41 to 46 N•m [30 to 34 lbf•ft]

16
Series 26 - Model 26000 Multiple Gear Pump
Placing Series 26 Gear Pump
Back into Operation
Connect
to
Fluid Supply
Mount Pump
on
Machine
Check
for
Leaks
Pump
Ready for
Service
Start Pump
and
Run For
3 Minutes
Each
At 1/2 Speed At 1/2 Speed At Full Speed
At
Zero
Pressure
Load
Intermittently
to 1000 lbf/in2
Load
Intermittently
to 500 lbf/in2
When test stand is not available .
When test stand is
available .
Connect
to
Fluid Supply
Mount Pump
on
Test Stand
Check
for
Leaks
Pump
Ready for
Service
Start Pump
and
Run For
3 Minutes
Each
At
Zero
Pressure
Load
Intermittently
to 1000 lbf/in2
Load
Intermittently
to 500 lbf/in2
Remove
from
Test Stand
Load
Intermittently
to 2000 lbf/in2

17
Series 26 - Model 26000 Multiple Gear Pump
Trouble Shooting
Problem Possible Cause Correction
Cavitation a. Oil too heavy. a. Change to proper viscosity
b. Oil filter plugged. b. Clean filter.
c. Suction line plugged or too small. c. Clean line and check size of line.
Oil heating a. Oil supply low. a. Fill reservoir.
b. Contaminated oil. b. Drain reservoir and refill with clean oil.
c. Setting of relief valve too high or
too low. c. Set to correct pressure.
d. Oil in system too light. d. Drain reservoir and refill with proper
viscosity oil.
Shaft seal leakage a. Worn shaft seal. a. Replace shaft seal.
b. Worn shaft in seal area. b. Replace drive assembly.
c. Debris in shaft seal suction side
drain holes. c. Disassemble pump and inspect.
Foaming oil a. Low oil level a. Fill reservoir.
b. Air leaking into suction line b. Tighten fittings.
c. Wrong kind of oil. c. Drain and fill reservoir with
non-foaming oil.

18
Series 26 - Model 26000 Multiple Gear Pump
Note
Wear Plate Identification
A product improvement has been made to the Model 26000 gear pump with a new designed wear plate. To identify the new wear
plate, look for grooves placed in the seal side of the wear plate as shown below.
This new wear plate enables better pressure clamping with aerated oil in pumps 1.37 cubic inch or smaller. Aerated oil
may occur during a cold start-up in applications with long suction lines or when the mouth of the inlet line is temporarily
exposed to air.
New Groove
New Groove
New Groove
OLD
Wear Plate
NEW
Wear Plate

19
Series 26 - Model 26000 Multiple Gear Pump
Note

Order parts from 6-635 Parts Information booklet.
Each order must include the following information.
1. Product and/or Part Number
2. Serial Number Code
3. Part Name
4. Quantity