We service Denison hydrostatic pumps

We repair Denison Hydrostatic Pumps

Port Assembly

• Put in the port block (1) on a clean flat area with the two open ports up. THE OTHER SIDE OF THE FACE MUST NOT BE SCRATCHED OR DAMAGED. PLACE needle bearing (2) on tool (Figure T-5) with the labeled end of the bearing next to the shoulder on the tool and press the bearing (2) into the port block. The bearing must be .010-025 below the surface.
• Condense check ring (3) and slip into the two 1.50" ports and corresponding holes in the ring with the side holes in the port wall.
• Need lock washers (6) on particular screws (5). Put in (5) throughout the port wall and drilled holes in checks (3) and thread into clamps (4). Torque to 10ft. ids. There is only need for one check assembly on open loop pumps.
• Strand the socket pipe plugs (8) into port block.
• Pass through two check valve assemblies (7) into valve face of port block.
• Place O-ring (10) on hollow hex plug (9) and thread into tapped hole in top of the port block.

MOUNTING PORT BLOCK ASSEMBLY See Figure 8

Put the pump with the unplugged hole in the housing assembly at the 12 o'clock spot.

Place the gasket (5) on the housing assembly (6).

Mount the two special pins (3) in the face of the port block assembly. Submit an application of petroleum jelly or heavy grease to the plate (4) and pose port plate over the pins (3) on the port block.

Slip the port block assembly and port plate over the end of the secondary shaft. Always make certain that tubes 2, 3 and 4 shown on Fig. 4 are seated and that the port plate (4) is at rest on the pins (3).

As soon as the pump is correctly assembled, the valve-mounting surface will be at the top of the unit.

Fit the four bolts (1), and torque to 150ft. Ibs.

WARNING : USE CARE TO AVOID DAMAGE TO THE VALVE MOUNTING AREA WHILE PUTTING TOGETHER AND TORQUING THE TWO TOP BOLTS

PORT BLOCK ASSEMBLY (Fig. 7)

No.	Qty.	Pirt No.	Description
1	1	o33-zi2aa	Port block (P & D units)
	1	033-71911	Port block (V units)
2	1	230-82146	Needle bearing
3	2	033-70502	Check ring
4	2	033-70489	Clamp
5	2	033-70908	Face plate pins
1	2	033-71921	Special screw
6	2	348-10016	No. 10 Lock washer
7	2	S1 3-40266	Check valve assy. (3/8-24 ext. thrds.)
8	2	431-90404	1/4" Soc. pipe plugs
9	1	488-35041	Hollow hex plug SAE-6
10	1	691-00906	O-ring 90-6290-6
Qty	1	Req'd. for items 3, 4, 5, 6 & 7 for P6V units

PARTS LIST FOR FIGURE 8

No.	Qty.	Part No.	Explanation
1	4	306-40182	Hex head cap screw 5/8-1 1x9
2	1		Port block assembly (see #1 above)
3	2	033-49825	Port plate pins
4	1	033-71526	RH port plate 6 in3 P & D units
	1	033-71903	RH port plate 6 in3 V units
	1	033-71525	LH port plate 6 in3 P & D units
	1	033-71904	LH port plate 6 in3 V units
	1	033-72811	RH port plate 7.25 in3 P & D units
	1	033-53388	RH port plate 7.25 in3 V units
	1	033-53776	LH port plate 7.25 in3 P & D units
	1	033-72937	LH port plate 7.25 in3 V units
5	1	033-70577	Housing gasket
6	1	S1 3-42335	Housing assembly
7	1	See Fig. 4	Mounting flange

Housing Assembly

See Figure 5

• Place housing (1) on a clean flat area with the large open end up.
• Put bearing (2) in the housing bore. Put in Pressing Plug tool (figure T-4) in the bearing. With an even amount of steady pressure, press the bearing into the housing bore until seated.

HAMMERING OR BEATING INTO PLACE IS NOT RECOMMENDED

• Rotate housing (1) on side and put together roll pin (4) in the Vi" through hole in the control cover pad. The pin needs to be 3/8" under the pad area. THE PIN END SHOULD NEVER COME IN CONTACT WITH THE INTERNAL BEARING CAGE. Take two dowel pins (3) in the blind holes in the same pad.
• Do this operation 3 on the opposite side of the housing.

Always check to make sure the faceplate is properly seating on the barrel and pins with the steel side facing the barrel face. The Series 7.25 has only one side bronzed and this should be toward the port plate. If essential, remove coating from edge of faceplate to establish bronze side.

• Put in the gasket (3) over the two dowel pins(item 6 on Fig. 4) in the mounting flange
• Position the Housing assembly (4) over the Barrel and Auxiliary Shaft assembly and carefully guide the pressure tubes and tube lines (items 2, 3 and 4 on Fig. 4) through the Housing assembly (4).

Situate the pump in an horizontal position with the port block inlet and outlet pads turned facing down.

Setup the shaft and bearing (1) assembly in the mounting flange and cradle. Always check to see that there are no burrs or sharp edges on shaft seal surface of the shaft.

For a stiff shaft application use the shim (2) that results in the smallest amount clearance around the shaft bearing. It is very important not to use a shim with a floating shaft.

Fit the snap ring (3) in the mounting flange to keep the Shaft Assembly. Always line up the ring so that it is fully seated in the groove. The ring with the tightest fit is going to give the best results.

SEAL ASSEMBLY

The seal assembly (4) comes as a complete unit only.

Warning : Previous to installing the seal assembly inspect all the parts. The lapped seal seat and the carbon ring have a meticulousness finish that must be handled with care. Certainty that both parts are free of scratches, marks and cracks.

Rest the spring retainer (e) over the shaft and alongside the retaining ring on the shaft assembly. Situate the spring (d) alongside the retainer (e). Apply grease to the inside surface of the rubber friction ring (f) and arrange the shell containing the rubber friction ring (f) and carbon ring (c) over the shaft with the carbon ring uncovered. Apply grease to the square segment rubber seal (a) and fit on the cast iron seat (b). Insert the seat and seal in the seal retainer (6) with the lapped side of the seat in position to contact the carbon ring. Place the seal retainer assembly and gasket (5) over the shaft with the lapped surface beside the carbon face. Set the four gaskets (7) on the four screws (8) and include the seal retainer (6). Lower the seal retainer only far as necessary to start the four screws and tighten equally. Torque to 10 ft. Ibs.

NOTE

To avoid the rubber friction ring from seizing on the shaft the seal installation should be done as quickly as possible.

COUNTER-BALANCE SERVO STEM ASSEMBLY

Consign the two spacers (11) on the two screws (12) and put in through the balance plate (10) and servo stem (9).

Introduce these parts through the opening in the side of the housing assembly and place the screws over the two 10-24 tapped holes in the rocker cam.

Embrace these parts adjacent to the cam and alternately tighten the screws (12) to hold the assembly steadfastly in place. Torque screws to 5 ft. Ibs.

Problem Solving

No.	Qty.	Part No.	Explanation
1	1	S15-41806	No. 2 Keyed Shaft Assy. See Fig. 1
2	1	033-53948	Shim
	1	033-53949	Shim (use only 1)
3	1	033-53901	Retaining Ring (use only 1)
	1	033-53902	Retaining Ring (use only 1)
	1	033-53903	Retaining Ring (use only 1)
4	1	62340006	Shaft Seal
5	1	033-70549	Seal Retainer Gasket
6	1	035-70516	Seal Retainer
7	4	631-45003	Nyltite Gasket
8	4	306-40144	Screw
9	1	033-71312	Servo Stem
10	1	033-70546	Balance Plate
11	2	033-71247	Spacer
12	2	358-10300	10-24 x 2-V. Soc. Hd. Cap Screw
13	8	631-45007	Nyltite Washer
14	8	353-25018	3/8-16 x 1-% Hex Washer Hd. Screw
15	1	See Below	Output Control Assy.
16	1	See Below	Input Control Assy.
17	8	306-40184	3/8-16 x 3% Hex Hd. Cap Screw
18	1	671-00017	O-Ring
19	1	671-00048	O-Ring

Cautiously take away the carbon ring and the remnants of the shaft seal from the shaft.

Warning

Do not scratch seal exterior of shaft when removing seal.

Eradicate the snap ring (3) and the shaft and bearing assembly (1) and take away shim (2).

HOUSING I

Following the shaft assembly that has been set aside, arrangement of the unit on the end with the mounting flange turned face down.

• Pressing the ends of the small tube lines away from the housing.
• Raise up the housing from the mounting flange, eliminate the gasket, and dowel pins from the mounting flange.
• Do not take away the roll pins and the bearing from the housing unless the bearing has been damaged and needs to be replaced.

ROCKER CAM AND CONTROL STROKING ASSEMBLY See Figure 4

Get rid of the whole assembly from the mounting cap and place on a clean flat surface with the two tubes (2) in a straight position and located at the top. Label the cam (24) and cradle (20) as indicated in Figure 3.These labels can decide positioning of parts during reassembly.

Cautiously remove the small tube lines (3) and (4) from the cradle.

IT IS IMPORTANT NOT TO BEND THE LINES.

Arranging of the assembly in an erect position on the flat surface of the cradle (20). Do away with the retaining ring (1) and thrust washer (2). Along with the piston and shoe assembly (4) and the creep plate (5) from the cam (24). With awareness remove the two setscrews (6a) and two screws (6) that secure the servo plate to the cam (24) and lay aside the servo input parts (7, 8 and 9).

Remove the four 7/16" screws (10) and eight V*" screws (11) and (12) from the control covers (15R) and (15L). and the four dowel pins (16), remove the two chambers (17), remove the two special seals (18) and the four steel balls (19). Also remove the two vane seal cartridge assemblies (23) and the four-holddown vanes (22) from the rocker cam (24).

NOTE

A number of units may have thin shims under the hold-down vanes. Eradicate the rocker cam (24) from the cradle (20). DO NOT TAKE THE PLUGS FROM THE ROCKER CAM.

REVISE LIMITS OF WEAR PARTS

6 and 7.25 in.3	Original Dimension	Max. Rework From Original Dimension	Min. Dimension After Rework
Port plate face	.315/.305"	.010"	.295"
Cylinder barrel face	4.480"	.010"	4.470"
Shoe retainer face	.314/.312"	.005"	.307'
Piston shoe face (pocket)	.019/.014"	.011/.006"	.008"
Creep plate face	.293/.291"	.010"	.281"
Face plate		none	Replace

Unit Disassembly

The directions enclosed in this section cover a entire break up of the subject pump. Disassemble only as far as required to replace or repair any worn parts.

DISASSEMBLY

Place pump unit so that valve block assembly is on top. Work on a clean work area such as a stable work station competent enough of supporting the unit

CONTROLS See Figure 11

Take away the four screws (14) from the side (16) and do away with the input shear seal valve assembly.

Do away with the four screws (14) from the side cover (15) and eliminate the counter balance shear seal assembly.

Take away the two screws (12) and take out the servo stem (9) and balance plate (10).

VALVE BLOCK See Figure 11

Eradicate the eight hex head cap screws (17) and lift the whole block assembly from the port block.

VALVE COVER See Figure 10

• Take out the four screws (39) to divide the cover (21) from the block (11). Do not take away the check valves (19),
• Place aside the plugs (43), (36) and pin (40). Put aside the 8-32 nut from the bottom of cover (21) to remove filter assembly (34).
• Put housing (29) and O-Ring (28), items (30)7^(31), (32) and (33) as a unit. Put in a small brass rod thru the hole in the housing and tap out piston (27) and O-ring (26).
• Place a spring (25) and cone (24). Take away the seat (23) and O-ring (22).

Note: Seat is ready for hex wrenching. Use %" 6 point socket with %" drive.

VALVE BLOCK

• Lay aside the O-ring (37) and replenishing release valve (41). Examine the orifices (12) visually to insure they are open. Do not remove unless damage or clogging is visible.
• Springs need to be removed (16), (17) and (18). Next the retainer (15) and poppets (13) arid (14) have to go.

RETAINER PLATE

Set aside the four screws (4) from the plate (6) and (11), gasket (7).

Doing away with the seats (8) and (9). Do not eliminate Rolf

pins (5) and (10) unless replacements are needed.

BARREL HOLODOWN AND GEROTOR ASSEMBLY See Figure 9

• Taking away the snap ring (17), end cover (15) and "O" ring (16).
• Removing the pin (14), retainer ring (18), hold down nut (13), thrust washers (10), bearing (11) and seal ring (12).
• The pressure plate needs to be moved away from (9), Gerotor side plate (5a) "O" rings (7) and (8), needle bearing (5b).
• Do away with the Gerotor assembly (3), dowel pin (4), key (2), and side plate (1).

PORT BLOCK See Figure 8

• Removing the four screws (1) that secure the port block (2) to the housing (6). Use the correct measures when getting rid of screws on valve block side to prevent marring valve block face.
• Taking away the port block (2), gasket (5), port plate (4) and port plate pins (3).
• Remove the check valve assemblies (7) from the port block.
• Next take away the needle bearing (2) from the port block.
• Then eliminate two screws (5), lock washers (6), check rings (3), and clamps (4). Only one check ring assembly in open loop pumps.

BARREL AND AUXILIARY SHAFT

• Take away face- plate (2, fig. 6) from face of barrel assembly.
• Get rid of the barrel assembly (1, fig. 4) by grasping the auxiliary shaft and lifting the whole assem bly out of the housing.

DRIVE SHAFT See Figure 11

Take away the four screws (8) and gaskets (7). Eriadicate seal retainer (6), and the stable part of the shaft seal (4). Refer to view of item 4.