Specifications, Service and Repair of Farm and Lawn Tractors


Case 485, 385 Tractor Speed transmission – 2 speed power shift


Case 385, 485, 585, 685, 885 Tractors may be equipped with a two speed Power Shift unit located in front of the speed trans-mission.

The two speed unit is controlled by an electric solenoid/hydraulic valve.

The two position control switch is located on left side of instrument panel.

When shifted from high (direct) drive to low drive, tractor power is increased with a 17 percent reduction in speed in any tractor gear without interruption of engine power.

This gives the tractor a total of sixteen forward speeds and eight reverse speeds.

Regulator (control) valve


The regulator (control) valve (4) and bottom core plate (12) can be removed from Case IH 485, 385 tractor without removing the speed gearbox.

All other service on the Power Shift unit requires removal of complete speed gearbox.

Fig.20. Power Shift regulator (control) valve and bottom core plate with relative components removed from Case 485, 385 speed transmission gearbox

1.Screen, 2.Plug, 3.Wire clip, 4.Regulator (control) valve assy, 5."O" rings, 6.Pressure tubes, 7.Oil inlet tube, 8.Power shift cable, 9.Solenoid cable, 10.Plug, 11.Solenoid wire shield, 12.Bottom core plate, 13.Gasket, 14.Separator plate, 15.Gasket

To remove the regulator valve and bottom core plate, first disconnect battery ground cable. Remove drain plug and drain transmission fluid.

On Case 485, 385 tractor equipped with front drive axle, unbolt and remove drive shaft shield and front drive shaft. On all models, unbolt and remove solenoid wiring shield (11).

Disconnect the Power Shift cable (8) from solenoid cable (9) at connector. Unbolt bottom core plate (12) and remove from speed gearbox.

Fig.21. Regulator (control) valve and solenoid

1.Solenoid, 2."O" ring, 3."O" ring, 4.Screw (2), 5.Clamp, 6.Valve body, 7.Spool, 8.Spring, 9.Plug, 10.Valve, 11.Spring, 12.Pin, 13.Washer, 14.Plug

Disconnect wiring from solenoid, then unscrew union and remove wiring and union from core plate (12). Remove screws (4), clamp (5) and solenoid (1) with "o" rings (2 and 3).

Remove regulator valve end cap (14), washer (13), pin (12), spring (11) and valve (10). Remove plug (9), spring (8) and spool (7).

Unbolt and remove regulator valve body (6), then remove filter screen (1) from bottom of valve body. Remove gasket (15), separator plate (14) and gasket. (13) from core plate (12).

Remove oil inlet tube (7). Oil tubes (6) will remain in speed gearbox housing.

Clean and inspect all parts for excessive wear or other damage and renew as necessary. Body (6), spool (7) and plug (9) are not serviced separately.

When reassembling, use new "O" rings (2 and 3) and new gaskets (13 and 15) and "O" rings (5) and reverse disassembly procedures.