Specifications, Service and Repair of Farm and Lawn Tractors


Case 485, 685 Tractor steering hand pump


To remove the steering hand pump, proceed as follows: On Case IH 485, 685 Tractor without cab, remove battery access panel and disconnect battery cables. Unbolt and remove upright muffler. Remove radiator cap, tractor hood and side panels. Remove battery and insulation pad from battery tray.

Using a suitable puller, remove steering wheel. Remove nut from ignition switch and push switch to inside. Unbolt and remove instrument panel side panels. Unbolt instrument panel and raise about 2 inches (50 mm) on right side and support in this position.

On Case IH 685, 485 Tractor with XL cab, remove battery cover, disconnect battery cables and remove battery. Using a suitable puller, remove steering wheel.

Push in and turn lockpins, then lift off the instrument panel front housing. Loosen locknut and remove engine stop control knob. Remove locknut and grommet from instrument panel.

Disconnect tachometer cable. Lift instrument panel upward to clear steering shaft, then move the panel to the right and support assembly in this position.

On all models, identify and disconnect the four steering hoses from hand pump. Plug or cap all openings. Remove the two hand pump retaining cap screws and lower the unit. Remove the two spacers, then remove hand pump assembly.

To disassemble the steering hand pump, clean exterior of assembly, then unbolt and remove steering shaft and column. Scribe match marks across end cover (32—Fig.11), stator (30), distributor plate (27) and housing (9). Clamp valve housing in a soft jawed vise in inverted position and remove end cover cap screws.

Remove end cover (32), stator (30), spacer (25), rotor (28), distributor plate (27) and drive shaft (24). Using a screwdriver and a magnet, unscrew and remove threaded bushing (14) and ball (13).

Remove unit from vise and shake suction pins (11) and balls (10) from housing. DO NOT use a magnet to remove pins and balls. Push valve spool assembly from housing.

Remove thrust washers (16 and 18), needle bearing (17) and retaining ring (19) from end of spool. Remove cross pin (21) from spool, then slide spool (20) from sleeve (22). Remove inner and outer plate springs (23). Remove seal ring (15), "O" ring (12) and dust seal (8) from housing.

Using an Allen wrench, remove plug (1) with "o" ring (2). Note the position of the adjusting plug (3), then unscrew while counting the number of turns needed to remove the adjusting plug.

Record the number of turns to aid in reassembly. Remove spring (4) and relief valve (5). DO NOT remove seat (6) or check valve (7) as they are not available as replaceable parts.

Fig.11. Exploded view of the Danfoss steering hand pump

Clean and inspect all parts for excessive wear or other damage. If housing (9), seat (6), check valve (7), spool (20), sleeve (22), rotor (28) or stator (30) are not suitable for further service, renew complete hand pump assembly as these parts are not serviced separately.

All' 'O'' rings, seals and plate springs are available in a seal kit. Check rotor (28) and stator (30) for wear as follows: Refer to Fig.2 and measure thickness of rotor at (A) and stator at (B).

If (A) is 0.002 inch (0.051 mm) less than (B), renew hand pump. Refer to Fig. 12 and place rotor in stator as shown. Using a feeler gage, measure gap as shown. If gap is 0.005 inch (0.127 mm) or more, renew hand pump assembly.

Fig.12. When checking rotor and stator, measure distance "A" on rotor

Fig.13. Distance "B" on stator

Reassemble by reversing the disassembly procedure keeping the following points in mind. Lubricate all internal parts with Hy-Tran Plus fluid and coat all "O" rings with petroleum jelly during reassembly.

When installing plate springs (23—Fig.11), first install the two flat springs. Then, install the two curved springs (arches back to back) in between the two flat springs.

When installing rotor (28) on shaft (24), make certain that cross pin slot in shaft aligns with center of a valley in rotor. Align match marks and tighten end cover cap screws (35) to a torque of 22-26 ft.-lbs. (30-35 N-m).

Fig.14. Use a feeler gage to measure gap between rotor and stator

Reinstall steering column and upper shaft on pump and tighten cap screws to a torque of 33-37 ft.-lbs. (45-50 N-m). Install hand pump and two spacers in place, then install the two retaining cap screws and torque to 33-37 ft.-lbs. (45-50 N-m).

With pump installation completed, install all removed parts (battery, hood, panels and instrument panel) except access panel to adjust relief valve (5) pressure.

Refer to paragraph 23 and adjust relief valve pressure as follows: Remove plug (1—Fig.11) and with engine operating at 1000 rpm, check relief pressure on gage.

Pressure should be 2150 psi (14825 kPa). Turn adjusting plug (3) inward to increase pressure or outward to decrease pressure. Install and tighten plug (1) and complete balance of installation.

Case 485, 685 Tractor steering hand pump test

To test the steering hand pump, disconnect steering hose from left end of steering cylinder. Cap cylinder fitting. Connect a hose and 4000 psi (28000 kPa) test gage to the steering hose. Remove center cap from steering wheel.

Fig.15. Exploded view of the multiple control valve assembly

With engine stopped, use a torque wrench and apply 52 ft.-lbs. (70 W-m) of torque to the steering wheel nut in a counterclockwise direction.

Check the reading on the test gage. Pressure reading should be not less than 55 psi (380 kPa).

If pressure reading is not correct, check for the following conditions:

- Worn Case IH 485, 685 Tractor steering hand pump or damaged seals.

- Worn or stuck cheek ball in hand pump.

- Stuck check valve in pressure inlet port of hand pump.

Then, with engine operating at 1000 rpm, turn steering wheel counterclockwise and check pressure gage reading. Pressure should read 2150 psi (14825 kPa).

If pressure reading is not correct, check for following conditions:

- Relief valve stuck in hand pump. Incorrect relief valve setting.

- Correct the problem and retest.

- Remove pressure gage and connect steering hose to cylinder.