Eaton 70422 Owner's manual

Eaton®
Medium Duty Piston Pump
Model 70422 or 70452
0 - 38 cm3/r [0 - 2.32 in3/r]
Displacement
Parts and Repair
Information
No. 6-631
January 1998
Model 70423 or 70453
0 - 45 cm3/r [0 - 2.77 in3/r]
Displacement
Pressure or Pressure-Flow Compensated Piston Pumps

2
Model 70422 or 70423
Table of Contents
Introduction.........................................................................................................2
Identification........................................................................................................3
Tools Required ....................................................................................................3
Parts Drawing......................................................................................................4
Parts List .............................................................................................................5 - 15
Item 1 - Drive Shaft ID ..................................................................................6
item 2 - Backplate Assembly .........................................................................7 - 8
Item 4 - Compensator Assembly and Parts List ............................................9 - 10
Factory Pre-set Compensator Assemblies.....................................................11
Item 3 - Housing Identification......................................................................12
Item 5 - Rotating Kit......................................................................................12
Mounting Kits................................................................................................13
Product Number............................................................................................14 - 15
Repair information...............................................................................................16 - 18
Disassembly..................................................................................................16
Inspection .....................................................................................................17
Reassembly...................................................................................................17 - 18
Start-up Procedure ..............................................................................................19
Fault - Logic Troubleshooting..............................................................................20 - 23
Introduction
This manual provides service information for the Eaton Models 70422 or 70423 Pressure or Pressure - Flow
Compensated Piston Pumps. Step by step instructions for the complete disassembly, inspection, and
reassembly of the pump are given. 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.
Lubricate the new rubber seals with a petroleum jelly (Vaseline) before installation.
Torque all bolts over gasketed joints, then repeat the torquing sequence to make-up for gasket
compression.
Verifying the accuracy of pump repairs on an authorized test stand is essential.
Introduction

3
Model 70422 or 70423
Identification and Tools Required
•9/16 Inch Socket
•1-1/8 Inch End Wrench
•11/16 Inch End Wrench
•Rachet Wrench
•Torque Wrench (100 lb./ft.)
•3/16 Inch Hex Key (Allen)
•3/16 Inch Hex Key (Allen Socket)
•Soft Face Hammer
•Internal Retaining Pliers (Straight .070 Tip)
•External Retaining Pliers (Straight .070 Tip)
•Regular or Locking Pliers
•Seal Driver or Similar Tool
•Petroleum Jelly (Such as Vaseline)
•3/8 inch I.D. x 1-1/8 inch O.D. flat washer (2 ea.)
•3/8 inch x 3-1/4 inch N.C. Cap screw (1 ea.)
•3/8 inch N.C. Nut
Tools Required
Identification Numbers - Pressure or Pressure-Flow Compensated Piston Pump
Stamped on each units mounting flange.
A - Product Number Description
70422 = Single Piston Pump
70452 = Single Piston Pump, w/ Aux. Flange
70423 = Single Piston Pump
70453 = Single Piston Pump, w/ Aux. Flange
B - Rotation
L - Left Hand (CCW)
R - Right Hand (CW)
C - Sequential Numbering
Single Pump - Product Number:
7 0 4 2 3 - R A A
A
Serial Number Code:
B 93 01 31 JB Testers Initials
Day of Month (two digits)
Month (two digits)
Revision level of parts list.
Last two digits of year built.
( 93 for 1993 etc.)
B C
Year Manufactured
(1 for 1991 etc.)
Change Code
Serial Number Code prior to Jan., 1992:
1 B- 52-JB Testers Initials
Week of Year

4
Model 70422 or 70423
Parts
Drawing
Pump drawn below is typical of a righthand (CW) rotation pump.
19 28
427
35
(Cover only)
5
7
26
3-1
12
21
12
10
20
11
14 23 815 24
24 15 823 14
13
18 17
9
3-2
1
2122
6
25
2
16
Serial code and
assembly number location
3
All left (CCW) or right (CW) directions
given are viewed from the input shaft end of the pump.

5
Model 70422 or 70423
Parts List
Item Part No. Qty. Description
1♦1 Drive Shaft (Identification drawing on page #6)
2♦1 Backplate Assembly (Identification drawing on page #7 & 8)
3♦1 Housing Assembly (Identification drawing on page #12)
3-1 16238-11816 1 Bearing
3-2 16026-808 2 Roll Pin
4♦1 Compensator Assembly (Identification drawing on page #9, 10, & 11)
5♦1 Rotating Kit Assembly (Parts list on page #12)
6 70423-605 1 Camplate, 0 - 38 cm3/r [0 - 2.32 in3/r] Displacement
6 70423-610 1 Camplate, 0 - 45 cm3/r [0 - 2.77 in3/r] Displacement
7 70421-401 1 Control Piston, 0 - 38 cm3/r [0 - 2.32 in3/r] Displacement
7 70423-418 1 Control Piston, 0 - 45 cm3/r [0 - 2.77 in3/r] Displacement
+ 8 16015-27 2 O-ring, 2.38 mm Dia. x 36.51 mm ID. [.0937 in. Dia. x 1.4375 in. ID.]
9 16026-608 1 Roll Pin
10 16048-319 1 Washer
+ 11 16077-32 1 Retaining Ring
+ 12 16078-18 2 Retaining Ring
13 17091-14 1 Spring
14 70412-151 2 Thrust Bearing
15 70412-607 2 Trunnion Cover
+ 16 70412-626 1 Gasket
17 70420-35 1 Pivot Button
18 70420-59 1 Spring Collar
+ 19 70422-600 1 Gasket
+ 20 16253-18 1 Shaft Seal
20 16253-218 1 Shaft Seal, Drive (fluorocarbon rubber)
21 74308-100 2 Thrust Bearing Race
22 74308-101 1 Thrust Bearing
23 70402-100 2 Inner Race
+ 24 16077-26 2 Retaining Ring
+ 25 16003-405-90 1 O-ring, 1.59 mm Dia. x 6.35 mm ID. [.0625 in. Dia. x .25 in. ID.]
26 16246-516 1 Key, Used on 19.05 [.75] diameter shaft
26 24500-619 1 Key, Used on 22.2 [.875] diameter shaft
27 16148-412 4 Cap Screw
28 16032-612 4 Cap Screw
32 170142-600 1 Cover Plate (In K3 kit)
33 16032-610 2 Cap Screw, Cover Plate (In K3 kit)
+ 34 16007-14 1 O-ring, (In K2 & K3 kit)
35 70422-618 2 Cover
Mounting Kits (Drawings and parts list on Page #13)
K2 70442-929 1 Gear Pump Mounting Kit (for "A" SAE flange)
K3 70142-915 1 Cover Plate Kit, (for "A" SAE flange)
K6 990596-000 1 Cover Plate Kit, (for "B" SAE flange)
K7 70453-901 1 Gear Pump Mounting Kit, (for "B" SAE flange)
Seal Repair Kit
• 70422-915 1 Seal Repair Kit
Legend ♦Refer to specific item parts list.
+ Included in seal repair kits listed.

6
Model 70422 or 70423
Item 1
Drive Shaft Identification
Item 1 - Drive Shaft Identification
Part Number Input Drive Output Drive
70442-235,
25.4 [1.0] Dia. Keyed
70402-201, 13 Tooth
70402-207, 15 Tooth
70402-204,
22.2 [.875] Dia. Keyed
9 Tooth
Internal
41 Tooth
External
9 Tooth
Internal
70452-200, 13 Tooth
70442-228, 15 Tooth
70442-225, 13 Tooth
70442-246, 15 Tooth
70442-231,
22.2 [.875] Dia. Keyed
9 Tooth
Internal
70402-206, 13 Tooth
w/ Retaining Ring Groove
Used with 2-bolt A Flange backplate
Used with 2-bolt B Flange backplate
Used with 2-bolt A Flange backplate
Used with 2-bolt A Flange backplate

7
Model 70422 or 70423
Item 2 - Model 70422 Backplate Assembly
(0 - 38 cm3/r [0 - 2.32 in3/r] Displacement)
Item 2 - Model 70422 Parts List (0 - 38 cm3/r [0 - 2.32 in3/r] Displacement)
Lefthand Righthand
Rotation Rotation
Item Part No. Part No. Qty. Description
2(a) 70421-318 70421-343 1 Rear Porting Backplate Assembly
2(b) 70421-327 70421-334 1 Opposite Side Porting Backplate Assembly
2(c) 70452-302 70452-304 1 Auxiliary 2-Bolt A Flange Series 82-2, Opposite Side Porting Backplate
2(d) --- 70452-317 1 Auxiliary 2-Bolt B Flange Series 101-2, Opposite Side Porting Backplate
2-170421-150 1 Bearing
2-216103-103 2 Plug Assembly
+ 2-2-116133-3 2 O-ring, 1.59 mm Dia. x 7.54 mm I.D.
[.0625 in. Dia. x .2969 in. I.D.]
2-370422-428 1 Guide Pin
Legend + Included in seal repair kit listed on page 7.
All left (CCW) or right (CW) directions
given are viewed from the input shaft end of the pump.
2-1
Lefthand Rotation
(CCW)
2-2
2-2-1
Righthand Rotation
(CW)
2-3
(Loctited)
Lefthand Rotation
(CCW) Righthand Rotation
(CW)
2(a )
Rear Porting
2(b)
Opposite Side Porting
2-2
2-2-1
Lefthand Rotation
(CCW) Righthand Rotation
(CW)
2(c)
Opposite Side Porting with 2-Bolt A Flange
Lefthand Rotation
(CCW) Righthand Rotation
(CW)
2(d)
Opposite Side Porting with 2-Bolt B Flange

8
Model 70422 or 70423
Item 2 - Model 70423 Backplate Assembly
(0 - 45 cm3/r [0 - 2.77 in3/r] Displacement)
Item 2 - Model 70423 Parts List (0 - 45 cm3/r [0 - 2.77 in3/r] Displacement)
Lefthand Righthand
Rotation Rotation
Item Part No. Part No. Qty. Description
2(a) 70423-303 70423-301 1 Rear Porting Backplate Assembly
2(b) 70423-306 70423-312 1 Opposite Side Porting Backplate Assembly
2(c) 70453-301 70453-303 1 Auxiliary 2-Bolt A Flange Series 82-2, Opposite Side Porting Backplate
2(d) --- 70453-307 1 Auxiliary 2-Bolt B Flange Series 101-2, Opposite Side Porting Backplate
2-170421-150 1 Bearing
2-216103-103 2 Plug Assembly
+ 2-2-116133-3 2 O-ring, 1.59 mm Dia. x 7.54 mm I.D.
[.0625 in. Dia. x .2969 in. I.D.]
2-370422-428 1 Guide Pin
Legend + Included in seal repair kit listed on page 5. All left (CCW) or right (CW) directions
given are viewed from the input shaft end of the pump.
2-1
Lefthand Rotation
(CCW)
2-2
2-2-1
Righthand Rotation
(CW)
2-3
(Loctited)
Lefthand Rotation
(CCW) Righthand Rotation
(CW)
2(a )
Rear Porting
2(b)
Opposite Side Porting
2-2
2-2-1
Lefthand Rotation
(CCW) Righthand Rotation
(CW)
2(c)
Opposite Side Porting with 2-Bolt A Flange
2(d)
Opposite Side Porting with 2-Bolt B Flange
Lefthand Rotation
(CCW) Righthand Rotation
(CW)

9
Model 70422 or 70423
Item 4 - Compensator Assembly
4-1
4-2 4-3 4-4
4-6
4-5
4-7 4-8
4-94-104-11
4-94-10
4-11
4-12 4-13
4-14
4-15
4-16
4-174-18
4-19-1
4-19
Lefthand (CCW) Pump Rotation Righthand (CW) Pump Rotation Fits Both Pump Rotations
(Righthand (CW) rotation shown)
Pressure-Flow Compensator Pressure Compensator
4(a) 70422-HU 4(b) 70422-HY 4(c) 70422-HR
*4-11, Cover not included with non-set compensator assy.
*4-11
Cover *4-11
Cover *4-11
Cover
non-set non-set non-set

10
Model 70422 or 70423
Item 4 - Compensator Parts List
Item 4 - Parts List (Refer to drawings)
Item Part No. Qty. Description
4(a) 70422-HU 1 Non-Set Pressure-Flow Compensator Assembly, Lefthand Rotation
4(b) 70422-HY 1 Non-Set Pressure-Flow Compensator Assembly, Righthand Rotation
4(c) 70422-HR 1 Non-Set Pressure Compensator Assembly
4-1N/S 1 Compensator Body
4-2N/S 1 Pressure Spool
4-370422-405 1 Spring Pivot Cap
4-417063-11 1 Spring
[phone] O-ring, 2.38 mm Dia. x 14.29 mm I.D. [.0937 in. Dia. x .5625 in. I.D.]
4-670421-453 1 Pressure Spring Follower
[phone] O-ring, 2.38 mm Dia. x 22.23 mm I.D. [.0937 in. Dia. x .875 in. I.D.]
4-870422-606 1 Adjustment Cap, Pressure
4-970422-620 1or2 Set Screw
4-10 16024-4 1or2 Nut
4-11* 70422-618* 1or2 Cover*
4-12 N/S 1 Flow Spool
4-13 70411-411 1 Spring Pivot Cap
4-14 17029-5 1 Spring
[phone] O-ring, 1.59 mm Dia. x 5.55 mm I.D. [.0625 in. Dia. x .2187 in. I.D.]
4-16 70421-477 1 Flow Spring Follower
[phone] O-ring, 1.98 mm Dia. x 11.89 mm I.D. [.078 in. Dia. x .468 in. I.D.]
4-18 70422-602 1 Adjustment Cap Flow
4-19 16103-103 2 Plug Assembly
+ 4-19-1 16133-3 2 O-ring, 1.59 mm Dia. x 7.54 mm I.D. [.0625 in. Dia. x .2969 in. I.D.]
Legend + Included in seal repair kit listed on page 5.
NSS Not Sold Separately
* Covers are not included with Non-Set Compensator
Factory Pre-set Compensator Assemblies listed on page #11.

11
Model 70422 or 70423
Pre-set Pressure-Flow Compensator Assemblies
Non-Set Pre-set
Assembly Assembly Pump Rotation Pressure Setting Flow Setting
70422-HU 70422-AY-03 Lefthand (CCW) 210±3.5 bar [3050±50 lbf/in2] 13.8±0.7 bar [200±10 lbf/in2]
70422-HU 70422-BH-03 Lefthand (CCW) 191±2.1 bar [2770±30 lbf/in2] 15.2±0.7 bar [220±10 lbf/in2]
70422-HU 70422-BL-03 Lefthand (CCW) 183±3.5 bar [2650±50 lbf/in2] 25.2±1.8 bar [365±25 lbf/in2]
70422-HU 70422-DE-03 Lefthand (CCW) 193±3.5 bar [2800±50 lbf/in2] 13.8±0.7 bar [200±10 lbf/in2]
70422-HU 70422-DU-03 Lefthand (CCW) 176±3.5 bar [2550±50 lbf/in2] 19.0±1.8 bar [275±25 lbf/in2]
70422-HU 70422-EQ-03 Lefthand (CCW) 210±3.5 bar [3050±50 lbf/in2] 25.9±1.8 bar [375±25 lbf/in2]
70422-HU 70422-GD-03 Lefthand (CCW) 176±3.5 bar [2550±50 lbf/in2] 17.2±1.8 bar [250±25 lbf/in2]
70422-HU 70422-GN-03 Lefthand (CCW) 155±3.5 bar [2250±50 lbf/in2] 19.0±1.8 bar [275±25 lbf/in2]
70422-HU 70422-GP-03 Lefthand (CCW) 169±3.5 bar [2450±50 lbf/in2] 19.0±1.8 bar [275±25 lbf/in2]
70422-HU 70422-HL-03 Lefthand (CCW) 210±3.5 bar [3050±50 lbf/in2] 24.5±1.0 bar [355±15 lbf/in2]
70422-HY 70422-BM-01 Righthand (CW) 210±3.5 bar [3050±50 lbf/in2] 13.8±0.7 bar [200±10 lbf/in2]
70422-HY 70422-BU-01 Righthand (CW) 131±3.5 bar [1900±50 lbf/in2] 13.8±0.7 bar [200±10 lbf/in2]
70422-HY 70422-DB-01 Righthand (CW) 238±3.5 bar [3450±50 lbf/in2] 13.8±0.7 bar [200±10 lbf/in2]
70422-HY 70422-DJ-01 Righthand (CW) 210±3.5 bar [3050±50 lbf/in2] 25.9±1.8 bar [375±25 lbf/in2]
70422-HY 70422-DW-01 Righthand (CW) 155±3.5 bar [2250±50 lbf/in2] 13.8±0.7 bar [200±10 lbf/in2]
70422-HY 70422-ED-01 Righthand (CW) 169±3.5 bar [2450±50 lbf/in2] 19.0±1.8 bar [275±25 lbf/in2]
70422-HY 70422-ET-01 Righthand (CW) 176±3.5 bar [2550±50 lbf/in2] 13.8±0.7 bar [200±10 lbf/in2]
70422-HY 70422-EZ-01 Righthand (CW) 176±3.5 bar [2550±50 lbf/in2] 17.2±0.7 bar [250±10 lbf/in2]
70422-HY 70422-FB-01 Righthand (CW) 191±2.1 bar [2770±30 lbf/in2] 15.2±0.7 bar [220±10 lbf/in2]
70422-HY 70422-FL-01 Righthand (CW) 193±3.5 bar [2800±50 lbf/in2] 20.7±1.0 bar [300±15 lbf/in2]
70422-HY 70422-FR-01 Righthand (CW) 210±3.5 bar [3050±50 lbf/in2] 19.0±1.8 bar [275±25 lbf/in2]
70422-HY 70422-GA-01 Righthand (CW) 172±3.5 bar [2500±50 lbf/in2] 20.7±0.7 bar [300±10 lbf/in2]
70422-HY 70422-GR-01 Righthand (CW) 193±3.5 bar [2800±50 lbf/in2] 17.2±1.8 bar [250±25 lbf/in2]
70422-HY 70422-GU-01 Righthand (CW) 210±3.5 bar [3050±50 lbf/in2] 17.2±1.8 bar [250±25 lbf/in2]
70422-HY 70422-HK-01 Righthand (CW) 210±3.5 bar [3050±50 lbf/in2] 24.5±1.0 bar [355±15 lbf/in2]
70422-HY 70422-HM-01 Righthand (CW) 176±3.5 bar [2550±50 lbf/in2] 24.5±1.0 bar [355±15 lbf/in2]
Pre-set Pressure Compensator Assembly
Non-Set Pre-set
Assembly Assembly Pump Rotation Pressure Setting
70422-HR 70422-CA-04 Both 210±3.5 bar [3050±50 lbf/in2]
70422-HR 70422-CH-04 Both 162±3.5 bar [2350±50 lbf/in2]
70422-HR 70422-CK-04 Both 148±3.5 bar [2150±50 lbf/in2]
70422-HR 70422-CL-04 Both 141±3.5 bar [2050±50 lbf/in2]
70422-HR 70422-CR-04 Both 107±3.5 bar [1550±50 lbf/in2]
70422-HR 70422-DH-04 Both 176±1.8 bar [2550±25 lbf/in2]
70422-HR 70422-FG-04 Both 159±3.5 bar [2300±50 lbf/in2]
70422-HR 70422-GE-04 Both 169±1.8 bar [2450±25 lbf/in2]
70422-HR 70422-HB-04 Both 190±3.5 bar [2750±50 lbf/in2]
70422-HR 70422-HE-04 Both 110±3.5 bar [1600±50 lbf/in2]
70422-HR 70422-HN-04 Both 114±1.8 bar [1650±25 lbf/in2]
Factory Pre-set Compensator
Assemblies

12
Model 70422 or 70423
Item 3 - Housing Identification
5-1
5-2 5-3
5-5
5-4
5-6 5-7 5-8
5-9
5-7
5
Item 3
Housing Identification
Item Part No. Port Machined
370402-304 A
70402-310 C
70402-336 B
70402-371 A, B
"A" Drain Port
.5625-18 SAE Straight Thd.
"B" Drain Port
.5625-18 SAE Straight Thd.
"C" Drain Port
Item 5 - Rotating Kit Assembly
Item Part No. Qty. Description
570402-638 1 Model 70422 Rotating Kit Assembly
0 - 38 cm3/r [0 - 2.32 in3/r] Disp.
570423-617 1 Model 70423 Rotating Kit Assembly
0 - 45 cm3/r [0 - 2.77 in3/r] Disp.
5-1NSS 9 Piston Assembly
5-2NSS 1 Spider
5-3NSS 1 Spider Pivot
5-4NSS 1 Retainer
5-5NSS 1 Piston Block
5-6NSS 3 Pins
5-7NSS 2 Washer
5-8NSS 1 Spring
5-9NSS 1 Retaining Ring
NSS - Not Sold Separately

13
Model 70422 or 70423
Mounting Kits
Kit 2, Gear Pump Mounting
(To Mount "A" SAE flanges)
Item Part No. Qty. Description
K2 70442-929 1 Gear Pump Mounting Kit
K2-1 16007-14 1 O-ring, 1.59 mm Dia. x 82.55 mm ID.
[.0625 in. Dia. x 3.25 in. ID.]
K2-2 16048-113 2 Washer
K2-3 16032-612 2 Cap Screws
Kit 3 & 6, Cover Plates
For "A" SAE Flanges
Item Part No. Qty. Description
K3 70142-915 1 Cover Plate Kit for "A" SAE flange
K3-1 16007-14 1 O-ring, 1.59 mm Dia. x 82.55 mm ID.
[.0625 in. Dia. x 3.25 in. ID.]
K3-2 70142-600 1 Cover Plate
K3-3 16032-610 2 Cap Screws
For "B" SAE Flanges (Not Pictured)
Item Part No. Qty. Description
K6 990596-000 1 Cover Plate Kit for "B" SAE flange
K6-1 102919-000 1 Gasket
K6-2 250073-000 1 Cover Plate
K6-3 95865-100 2 Cap Screws
K6-4 101896-050 2 Lock Washer
K3-1
K3-2
K3-3
K2-1
K2-2
K2-3
K7-1 K7-2
K7-4
K7-3
Kit 7, Gear Pump Mounting
(To Mount "B" SAE flanges)
Item Part No. Qty. Description
K7 70423-901 1 Gear Pump Mounting Kit
K7-1 70423-615 1 Coupler, 41 Tooth
K7-2 16007-17 1 O-ring, 1.59 mm Dia. x 101.6 mm ID.
[.0625 in. Dia. x 4 in. ID.]
K7-3 16008-0 1 Lock Ring
K7-4 16032-814 2 Cap Screws

14
Model 70422 or 70423
This list of product numbers is to aid in Item identification.
If your product number is not listed contact your Eaton representitive.
Model 70422, Lefthand Rotation (CCW)
Description of Part Number
Product Drive Shaft Backplate Assy. Housing Assy. Compensator Assy.
Number Item #1 Item #2 Item #3 Item #4
70422-LAG 70402-206 70421-318 70402-304 70422-CA-04
70422-LAH 70402-206 70421-318 70402-304 70422-AY-03
70422-LAY 70402-204 70421-318 70402-304 70422-CA-04
70422-LAZ 70402-204 70421-318 70402-304 70422-AY-03
70422-LBJ 70402-206 70421-327 70402-304 70422-AY-03
70422-LBK 70402-201 70421-327 70402-304 70422-CA-04
70422-LBL 70402-204 70421-327 70402-304 70422-AY-03
70422-LBM 70402-204 70421-327 70402-304 70422-CA-04
70452-LAG 70442-225 70452-302 70402-304 70422-AY-03
70452-LAJ 70442-225 70452-302 70402-304 70422-CA-04
70452-LAK 70442-231 70452-302 70402-304 70422-AY-03
Model 70422, Righthand Rotation (CW)
Description of Part Number
Product Drive Shaft Backplate Assy. Housing Assy. Compensator Assy.
Number Item #1 Item #2 Item #3 Item #4
70422-RAT 70402-206 70421-343 70402-304 70422-CA-04
70422-RAU 70402-206 70421-343 70402-304 70422-BM-01
70422-RCB 70402-204 70421-343 70402-304 70422-CA-04
70422-RCG 70402-204 70421-343 70402-304 70422-BM-01
70422-RDM 70402-201 70421-334 70402-304 70422-BM-01
70422-RDN 70402-206 70421-334 70402-304 70422-CA-04
70422-RDQ 70402-204 70421-334 70402-304 70422-CA-04
70452-RAG 70442-225 70452-304 70402-304 70422-BM-01
70452-RAJ 70442-231 70452-304 70402-304 70422-CA-04
70452-RAL 70442-231 70452-304 70402-304 70422-BM-01
Product Number
All left (CCW) or right (CW) directions
given are viewed from the input shaft end of the pump.

15
Model 70422 or 70423
This list of product numbers is to aid in Item identification.
If your product number is not listed contact your Eaton representitive.
Model 70423, Lefthand Rotation (CCW)
Description of Part Number
Product Drive Shaft Backplate Assy. Housing Assy. Compensator Assy.
Number Item #1 Item #2 Item #3 Item #4
70423-LBA 70402-204 70423-303 70402-304 70422-AY-03
70423-LBB 70402-201 70423-306 70402-304 70422-CA-04
70423-LBD 70402-204 70423-306 70402-304 70422-CA-04
70423-LBE 70402-204 70423-306 70402-304 70422-AY-03
70423-LBF 70402-201 70423-303 70402-304 70422-CA-04
70423-LBG 70402-201 70423-303 70402-304 70422-AY-03
70453-LAF 70402-207 70453-301 70402-304 70422-AY-03
70453-LAG 70402-207 70453-301 70402-304 70422-CA-04
Model 70423, Righthand Rotation (CW)
Description of Part Number
Product Drive Shaft Backplate Assy. Housing Assy. Compensator Assy.
Number Item #1 Item #2 Item #3 Item #4
70423-RBL 70402-204 70423-301 70402-304 70422-CA-04
70423-RBM 70402-204 70423-301 70402-304 70422-BM-01
70423-RBN 70402-201 70423-312 70402-304 70422-CA-04
70423-RBQ 70402-204 70423-312 70402-304 70422-CA-04
70423-RBS 70402-201 70423-301 70402-304 70422-CA-04
70423-RBT 70402-201 70423-301 70402-304 70422-BM-01
70453-RAG 70442-246 70453-303 70402-371 70422-BM-01
70453-RAJ 70442-235 70453-303 70402-371 70422-CA-04
Product Number
All left (CCW) or right (CW) directions
given are viewed from the input shaft end of the pump.

16
Model 70422 or 70423
Cleanliness is extremely important when repairing
these pumps. Work in a clean area. Before
disconnecting the lines clean port area of pump.
Disconnect hydraulic lines and remove pump
assembly from vehicle and plug ports. Thoroughly
clean the outside of pump. After cleaning, remove
port plugs and drain oil.
Disassembly
ATTENTION: Removal of the adjusting screw covers
from cap may void the warranty on this assembly.
1 Clamp the end of the drive shaft in a protected
jaw vise with the body of the pump up and remove
the four allen head screws (14) holding compensator
(4).
2 Remove the compensator assembly (4), 0-ring
(28), and gasket (24).
3 Remove the four cap screws (27) from the
backplate of the pump.
4 Place a screw driver in slots provided between
housing and loosen backplate. Remove backplate (2)
and gasket (21) from housing.
5 Remove the control piston (7) remaining on the
backplate or in housing. Also remove plug (2-2) from
backplate (2).
6 To remove rotating assembly (5) from housing,
remove pump from vise and slide rotating assembly
off shaft. Caution: pistons may not come out with
piston block.
7 Remove pistons (5-1), spider (5-2), and spider
pivot (5-3) from piston block (5-5).
8 The piston block assembly (5-5) need not be
disassembled unless the internal pins (5-6) or spring
(5-8) are damaged.
CAUTION: Use the following procedure if the spring
is to be removed from the piston block. The spring
(5-8) is highly compressed and the snap ring (5-9)
should not be removed without compressing the
spring.
The following parts will be needed to disassemble the
piston block:
2 ea. 3/8 l.D. x 1-1/8 O.D. flat washer,
1 ea. 3/8 x 3-1/4 N.C. cap screw, and
1 ea. 3/8 N.C. nut.
Place one of the flat washers over the 5/16 cap
screw and place this through the center of the piston
block. Place the other washer over the cap screw and
let it rest on the three pins. Screw the nut on and
compress the spring inside the piston block. Use a
pair of snap ring pliers and remove the internal snap
ring (5-9). Remove the nut and bolt along with the
two washers (5-7), three pins (5-6), and the internal
pin keeper (5-4).
9 To free shaft seal and shaft, remove retaining
ring (12).
10 Remove shaft (1) from housing (3) by tapping
backplate end of shaft with a wooden or plastic
mallet.
11 Remove shaft seal (17), washer (13), the two
retaining rings (10), the two thrust washers (16), and
bearing (15) from shaft.
12 To remove the camplate (6) from the housing,
remove the two internal retaining rings (11) from the
sides of the housing. Remove the two covers (20),
the two o-rings (26), the two inner races (19), and
the bearings (25). The camplate can now be moved
over to one side and removed. The two camplate
pivot bearings are a loose slip fit into the housing. Do
not be concerned if they are not tight.
13 Remove the spring collar (22) and spring (18).
Do not remove the button (23) and roll pin (9) unless
they are worn or loose.
14 The pressure-flow compensator assembly (4)
may be disassembled for cleaning and inspection.
Repair Information

17
Model 70422 or 70423
ATTENTION: Removal of the adjusting screw covers
from cap may void the warranty on this assembly.
15 Remove pressure adjustment cap (4-8) from
compensator housing (4-1). Pressure spring follower
(4-6) will remain in cap (4-8), pull follower from cap.
16 Remove flow adjustment cap (4-18) from
compensator housing (4-1). Flow spring follower (4-
16) will remain in cap (4-18). Pull follower from cap.
17 Remove springs (4-4 and 4-14) and spring pivots
(4-3 and 4-13) from compensator housing.
18 Remove plugs (4-19), pressure compensator
spool (4-2), and flow compensator spool (4-12) from
compensator housing (4-1).
19 The shaft seal, all 0-rings, and all gaskets should
be removed and replaced with new items upon
reassembly.
Inspect Parts For Wear
1 Inspect the flat surface of the backplate (2), the
finish on the piston block side should be smooth and
free of grooves. The piston guide should be tight in
the backplate. The needle bearing in the backplate
should be free of excessive play and remain in the
bearing cage. If the backplate has any of the wear
characteristics outlined above, replace complete
backplate assembly.
2 Inspect the piston block (5). The surface that
contacts the backplate should be smooth and free of
grooves.
3 The pistons (5-1) should move freely in the
piston block bore. If they stick in the bore, examine
the bore for scoring or contamination.
4 Examine the O.D. of the piston (5-1) for finish
condition. They should not show wear or deep
scratches. The shoes should be a snug fit on the ball
end of the piston. The flat surface of the shoes
should be flat, and smooth. Do not lap piston shoes.
5 Examine the spider (5-2). It should be flat, no
cracks, and no signs of wear in the pivot area.
6 Examine the pivot (5-3). It should be smooth and
show no signs of wear.
7 Inspect the camplate (6) for the condition of
finish of the polished shoe surface. It should show
no signs of scoring.
8 Inspect shaft (1) for wear in bearing and spline
areas.
9 Inspect thrust bearing (15) and thrust washers
(16) for wear.
10 Inspect the needle bearing in the housing
assembly (3). If the needles are free of excessive play
and remain in the bearing cage, there is no need to
replace the housing.
11 Inspect the compensator springs (4-4 and 4-14)
for breakage or weakness.
12 Inspect the spools (4-2 and 4-12) for scoring.
13 It is not necessary to inspect the o-rings,
retaining rings, gaskets, or shaft seal as they should
be replaced as new items and are included in the seal
repair kit available for this assembly.
Reassembly
1 Clean all parts in suitable solvent; lubricate all
critical moving parts before reassembly.
2 Install camplate control spring (18) and spring
collar (22) in housing (3).
3 Insert camplate (6) into housing (3). Insert
needle bearings (25) and bearing inner race (19) over
the camplate arms and slide into housing (3). The
numbered end of the bearing should face outward
and the chamfered l.D. of the race should face
inward.
4 Install new 0-ring (26) around O.D. of camplate
Repair Information

18
Model 70422 or 70423
pivot bearing (25). Install trunnion covers (20) and
secure with retaining rings (11).
5 Install retaining ring (10) on shaft (1). Install
thrust washer (16), thrust bearing (15), and second
thrust washer (16). Secure with second retaining ring
(10).
6 Install shaft (1) in housing (3) and install washer
(13), shaft seal (17), and retain with retaining ring
(12). Make sure retaining ring is seated in the
groove.
7 If piston block assembly was disassembled,
compress the pin keeper (5-4), and install in the
spline area of piston block. Install the three pins (5-
6) with the head end to the inside of the block and
install in the special grooves of the piston block
spline.
8 Install the washer (5-7), spring (5-8), and second
washer (5-7) in the piston block. Use the two 3/8 l.D.
washers and the 3/8 x 3-1/4 cap screw to compress
the spring and retain with retaining ring (5-9).
Remove the 3/8 cap screw and the two washers.
9 Install the pivot (5-3), spider (5-2), and piston
assemblies (5-1) in the piston block. Install this
assembly in the housing assembly, the piston shoes
must be in contact with the camplate. Be sure all the
parts are in their proper position.
10 Clamp this assembly in a protected jaw vise with
the open end of the housing (3) up.
11 Install new gasket (21).
12 Install control piston (7), and plug (2-2) with new
o-ring onto backplate. Note roll pin (3-2) locations.
13 Install backplate (2) and retain with cap screws
(27). Torque to 37 to 42 N-m [27 to 31 lb-ft].
14 Place new o-ring (4-19-1) on plug (4-19). Install
plug assembly, flow compensator spool (4-12),
spring pivot (4-13), spring (4-14), flow spring
follower (4-16) with new o-ring (4-15), and flow
adjustment cap (4-18) with new o-ring (4-17) into
compensator housing (4-1). Torque plug (4-19) 8 to
11 N-m [6 to 8 lb-ft] and torque flow adjustment cap
(4-18) 14 to 16 N-m [10 to 12 lb-ft ].
15 Place new 0-ring (4-19-1) on plug (4-19). Install
plug assembly, pressure compensator spool (4-2),
spring pivot (4-3), spring (4-4), pressure spring
follower (4-6) with new o-ring (4-5), and pressure
adjustment cap (4-8) with new o-ring (4-7) into
compensator housing (4-1). Torque plug (4-19) 8 to
10 N-m [6 to 8 lb-ft] and torque pressure adjustment
cap (4-18) 47 to 54 N-m [35 to 40 lb-ft].
16 Install new gasket (24) and new o-ring (28), then
install compensator assembly (4),and retain with
four allen head cap screws (14) and torque to 14 to
16 N-m [10 to 12 lb-ft].
17 Plug ports to preserve cleanliness until
installation on vehicle. (Refer to start up procedures.)
Repair Information

19
Model 70422 or 70423
When initially starting a rebuilt load sensing system,
it is extremely important that the start-up procedure
be followed. It prevents the chance of damaging the
pump which might occur if the system was not
properly purged with oil before start-up.
1 After the pump has been properly installed onto
the machine and all hydraulic connections have been
made, check all fittings to make sure that they are
tight.
2 Fill the pump housing at least 1/2 full with
system oil that has been filtered through a 10 micron
filter.
3 Fill the reservoir with an approved oil that has
been filtered through a 10 micron filter. Leave the
filler cap loose as a means of air that is trapped in the
system.
4 Note on gasoline or L.P. engines: remove the coil
wire and turn the engine over for 15 seconds. Diesel
engines: shut off the fuel flow to the injectors and
turn the engine over for 15 seconds. This procedure
enables the pump to pick-up the oil before start-up.
At this time disconnect the sensor line from the
pump compensator and pull one of the valve spools
while the engine is being turned over. This allows oil
to flow through the sensor line, thus, removing any
air in the sensor line. Reconnect the sensor line after
a steady flow of oil is coming from the line.
Start - up Procedure
5 Replace the coil wire or return the fuel flow to the
injectors and start the engine. Run at low idle speed
for one minute. The pump should immediately pick
up oil and go into low pressure standby. If there is no
indication of fill in 30 seconds, stop engine and
determine the cause.
6 After the pump has stabilized in low pressure
standby, operate the control valve and steering, if the
system is equipped with one, to purge the system of
air and to fill the cylinders with oil. Continue
operating the system slowly with no load until it
responds fully.
7 Check fluid level at the reservoir and refill if
necessary to the proper level at the reservoir and
refill if necessary to the proper level with an
approved filtered oil.
8 Check all line connections for leaks tighten if
necessary.
9 The machine is now ready to be put into
operation.
10 Short hour filter changes are recommended for
the first two changes after placing the machine back
into operation. The first filter would be changed in 3-
5 hours and the second at approximately 50 hours.
Routine scheduled filter changes are recommended
for maximum life of hydraulic system.

20
Model 70422 or 70423
Test Port
System Pressure - LH. Rotation
Inlet Vacuum - RH. Rotation
Fault - Logic
Troubleshooting
This fault - logic troubleshooting guide is a
diagnostic aid in locating pump problems.
Match the pump systems with the problem
statements and follow the action steps shown in the
box diagrams. This will give expedient aid in
correcting minor problems eliminating unnecessary
machine down time.
Following the fault - logic diagrams are diagram
action comments of the action steps shown in the
diagrams. Where applicable, the comment number of
the statement appears in the action block of the
diagrams.
Recommended Gauge Locations
Test Port
Inlet Vacuum - LH. Rotation
System Pressure - RH. Rotation
Load Sensing Port
Tee in Line to Check
Load Sensing Pressure
Drain Port
Tee in Line to Check
Case Pressure
Gauges Recommended
Inlet vacuum gauge: 2 bar to 1 bar [30 PSI to 30 inHg]
System pressure gauge: 700 bar [10,000 PSI]
Case pressure gauge: 0 to 25 bar [0 to 300 PSI]
1
Inspect
?
Repair
or
Replace
Defective
Action
Step
Comment
Number
Decision
Solution
Symptom:
Test Port
System Pressure - RH. Rotation
System Pressure - LH. Rotation
Load Sensing Port
Tee in Line to Check
Load Sensing Pressure
Drain Port
Tee in Line to Check
Case Pressure
Tee in Line to suction port for inlet
vacuum test. Suction port is the
largest port.
Model 70423
0 - 45 cm3/r [0 - 2.77 in3/r] Displacement
Model 70422
0 - 38 cm3/r [0 - 2.32 in3/r] Displacement