Servicedatasheet - PMCCatalogue

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Model 70422 or 70423Repair InformationCleanliness is extremely important when repairingthese pumps. Work in a clean area. Beforedisconnecting the lines clean port area of pump.Disconnect hydraulic lines and remove pumpassembly from vehicle and plug ports. Thoroughlyclean the outside of pump. After cleaning, removeport plugs and drain oil.DisassemblyATTENTION: Removal of the adjusting screw coversfrom cap may void the warranty on this assembly.1 Clamp the end of the drive shaft in a protectedjaw vise with the body of the pump up and removethe 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 thebackplate of the pump.4 Place a screw driver in slots provided betweenhousing and loosen backplate. Remove backplate (2)and gasket (21) from housing.5 Remove the control piston (7) remaining on thebackplate or in housing. Also remove plug (2-2) frombackplate (2).6 To remove rotating assembly (5) from housing,remove pump from vise and slide rotating assemblyoff shaft. Caution: pistons may not come out withpiston block.7 Remove pistons (5-1), spider (5-2), and spiderpivot (5-3) from piston block (5-5).8 The piston block assembly (5-5) need not bedisassembled unless the internal pins (5-6) or spring(5-8) are damaged.CAUTION: Use the following procedure if the springis 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 thespring.The following parts will be needed to disassemble thepiston 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, and1 ea. 3/8 N.C. nut.Place one of the flat washers over the 5/16 capscrew and place this through the center of the pistonblock. Place the other washer over the cap screw andlet it rest on the three pins. Screw the nut on andcompress the spring inside the piston block. Use apair of snap ring pliers and remove the internal snapring (5-9). Remove the nut and bolt along with thetwo washers (5-7), three pins (5-6), and the internalpin keeper (5-4).9 To free shaft seal and shaft, remove retainingring (12).10 Remove shaft (1) from housing (3) by tappingbackplate end of shaft with a wooden or plasticmallet.11 Remove shaft seal (17), washer (13), the tworetaining rings (10), the two thrust washers (16), andbearing (15) from shaft.12 To remove the camplate (6) from the housing,remove the two internal retaining rings (11) from thesides of the housing. Remove the two covers (20),the two o-rings (26), the two inner races (19), andthe bearings (25). The camplate can now be movedover to one side and removed. The two camplatepivot bearings are a loose slip fit into the housing. Donot 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) unlessthey are worn or loose.14 The pressure-flow compensator assembly (4)may be disassembled for cleaning and inspection.16
Model 70422 or 70423Repair InformationATTENTION: Removal of the adjusting screw coversfrom cap may void the warranty on this assembly.15 Remove pressure adjustment cap (4-8) fromcompensator 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) fromcompensator 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 compensatorspool (4-2), and flow compensator spool (4-12) fromcompensator housing (4-1).19 The shaft seal, all 0-rings, and all gaskets shouldbe removed and replaced with new items uponreassembly.Inspect Parts For Wear1 Inspect the flat surface of the backplate (2), thefinish on the piston block side should be smooth andfree of grooves. The piston guide should be tight inthe backplate. The needle bearing in the backplateshould be free of excessive play and remain in thebearing cage. If the backplate has any of the wearcharacteristics outlined above, replace completebackplate assembly.2 Inspect the piston block (5). The surface thatcontacts the backplate should be smooth and free ofgrooves.3 The pistons (5-1) should move freely in thepiston block bore. If they stick in the bore, examinethe bore for scoring or contamination.4 Examine the O.D. of the piston (5-1) for finishcondition. They should not show wear or deepscratches. The shoes should be a snug fit on the ballend of the piston. The flat surface of the shoesshould be flat, and smooth. Do not lap piston shoes.5 Examine the spider (5-2). It should be flat, nocracks, and no signs of wear in the pivot area.6 Examine the pivot (5-3). It should be smooth andshow no signs of wear.7 Inspect the camplate (6) for the condition offinish of the polished shoe surface. It should showno signs of scoring.8 Inspect shaft (1) for wear in bearing and splineareas.9 Inspect thrust bearing (15) and thrust washers(16) for wear.10 Inspect the needle bearing in the housingassembly (3). If the needles are free of excessive playand remain in the bearing cage, there is no need toreplace 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 shouldbe replaced as new items and are included in the sealrepair kit available for this assembly.Reassembly1 Clean all parts in suitable solvent; lubricate allcritical moving parts before reassembly.2 Install camplate control spring (18) and springcollar (22) in housing (3).3 Insert camplate (6) into housing (3). Insertneedle bearings (25) and bearing inner race (19) overthe camplate arms and slide into housing (3). Thenumbered end of the bearing should face outwardand the chamfered l.D. of the race should faceinward.4 Install new 0-ring (26) around O.D. of camplate17
Page 5 and 6: Model 70122Parts ListItem Part No.
Page 7 and 8: 8/7/2013Parcel ID Owners Name Legal
Page 9 and 10: Model 70122Item 4 - Compensator Par
Page 11: Model 70122Item 5 - Rotating Kit As
Page 14 and 15: Model 70122Repair Informationmay be
Page 16 and 17: Model 70122Start-up ProcedureWhen i
Page 18 and 19: Model 70122Fault - LogicTroubleshoo
Page 20 and 21: Model 70122Each order must include
Page 22 and 23: Model 70422 or 70423IntroductionTab
Page 24 and 25: Model 70422 or 70423PartsDrawingPum
Page 26 and 27: Model 70422 or 70423Item 1 - Drive
Page 28 and 29: Model 70422 or 70423Item 2 - Model
Page 32 and 33: Model 70422 or 70423Item 3 - Housin
Page 34 and 35: Model 70422 or 70423Product NumberT
Page 38 and 39: Model 70422 or 70423Repair Informat
Page 40: Model 70422 or 70423Fault - LogicTr
Page 48 and 49: Model 70523PartsDrawingPump drawn b
Page 50 and 51: Model 70523Item 1 - Drive Shaft Ide
Page 52 and 53: Model 70523Item 4 - Compensator Ass
Page 54 and 55: Model 70523Item 3 - Housing Identif
Page 56 and 57: Model 70523Product NumberThis list
Page 58 and 59: Model 70523Repair Informationfrom c
Page 60 and 61: Model 70523Start-up ProcedureWhen i
Page 62 and 63: Model 70523Fault - LogicTroubleshoo

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