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Case IH Tractor Independent PTO

The power take off used on Case IH Tractor 385/485/585/685 is an independent type. The pto is available as a single speed (540 rpm) unit or as a dual speed (540 and 1000 rpm) unit. Oil for the pto unit on tractor models is furnished from the hydraulic pump through the multiple control valve.

From the MCV, the oil is supplied through a cored passage in the rear frame to the 1000 rpm output shaft or lower pto drive shaft to actuate the pto clutch. Operation of the pto clutch unit is controlled by a spool type valve located in the MCV housing.

Pto control linkage adjustments

Although some checks and adjustments can be accomplished without removing left rear wheel, most mechanics prefer to remove the wheel to gain working room.

Fig.13. PTO control linkage used on Case IH Tractor 385/485/585/685 not equipped with cab

To adjust the pto linkage on tractor models without cab, refer to Figure and move control lever (1) for-ward and rearward to check total control spool movement. Total spool movement should be 1.14-1.18 inches (29-30 mm).

If not, remove pin (3), loosen lock-nut (4) and adjust clevis on link (5) to obtain correct total spool movement. Install pin and tighten lock-nut.

Make certain control lever has a small amount of clearance between lever and end of slot in console. If necessary, loosen clamp bolt (2) and while holding linkage in position move lever to adjust. Then, tighten clamp bolt.

Fig.14. PTO control linkage used on models equipped with cab

To adjust the pto linkage on models equipped with cab, refer to Figure and move control lever (1) forward and rearward to check total control spool movement. Total spool movement should be 1.14-1.18 inches (29-30 mm).

If not, remove pin (7), loosen lock-nut (6) and adjust clevis on link (5) to obtain correct total spool movement. Install pin and tighten lock-nut.

Check to see that control lever has a small amount of clearance at each end of slot in console. If necessary, remove pin (2), loosen locknut (3) and adjust clevis on link (4) until clearance is obtained. Install pin and tighten locknut.

Operating pressure test

To check operating pressure, operate tractor until hydraulic fluid is warmed to at least 100° F (38° C). Connect a 0-300 psi (0-2000 kPa) pressure gage (1) to the tee fitting (2).

Start tractor and operate at low idle speed. Move pto control lever forward to engaged position. Pressure reading on gage should be 260-270 psi (1790-1860 kPa).

If reading is correct, there is no problem in hydraulic system of the pto. If reading is not correct, remove test gage and remove pressure line from MCV to tee fitting.

Cap tee fitting and connect test gage to the pto outlet union on the MCV. Operate engine at low idle speed and move pto control lever forward to engaged position.

If pressure was low in first test but is now correct, check for following conditions and correct as required:

- Damage to lock ring seals on bottom pto shaft.

- Damage to pto shaft bushing in transmission housing.

- Damage to seals or piston in pto clutch of Case IH Tractor.

- If pressure is low in second test, there is a fault in the hydraulic supply, pto spool, regulator valve or MCV gasket.

With the 0-300 psi (0-2000 kPa) pressure gage still connected to the pto outlet union on the MCV, move pto control lever rearward into disengaged position. Reading on gage must be zero. A pressure reading on the gage would indicate that spool is not fully up or there is wear on the spool lands.

Move the control lever forward until the pto spool moves downward 0.39-0.43 inch (10-11 mm) (initial engagement position). Pressure reading should be 41-46 psi (283-317 kPa).

Record the gage reading, then move control lever fully rearward to disengaged position. Move control lever fully forward to engaged position. Gage reading should be 260-270 psi (1790-1860 kPa).

If initial engagement pressure is low but the full engagement pressure is correct, remove the pto spool assembly. See Figure. Inspect the spool lands and if in good condition, add a shim (7). Each shim will increase the initial engagement pressure 3 psi (21 kPa).

Fig.15. PTO control spool and regulator valve

If the initial engagement pressure is correct but the full engagement pressure is low, remove regulator valve (15 through 20), Inspect the regulator valve poppet (20) and seat and if in good condition, add a shim (17).

Each shim will increase the full engagement pressure 20-30 psi (138-207 kPa). Repeat pressure tests after adding shims or renewing any parts.

Case IH Tractor 385/485/585/685 PTO clutch, shafts and gears

Overhaul

To remove the pto clutch, first drain range transmission and remove clutch cover or transfer case, as equipped. Rotate upper pto output shaft until roll.

Drive roll pin from clutch and shaft. Unbolt and remove lower pto shaft cover or seal housing, as equipped, and remove gasket from rear of tractor.

Have helper support pto clutch and idler gears, if so equipped. Withdraw 1000 rpm output shaft (dual speed) or lower drive shaft (single speed). Remove idler gears, if so equipped, and pto clutch as shaft is withdrawn.

Fig.16. Pto clutch, gears and shafts. Inset shows the 1000 rpm shaft used In place of lower drive shaft

1-Shaft cover, 2-Bearing & seal retainer, 3-Gasket, 4-Oil seal, 5-Snap ring, 6-Washer, 7-Ball bearing, 8-540 rpm shaft, 9-Gear, 10-Snap ring, 11-Snap ring, 12-Needle bearing, 13-Snap ring, 14-"O" ring, 15-Idler shaft, 16-Needle bearing, 17-Idler gear, 18-Cover, 19-Gasket, 20-Snap ring, 21-Ball bearing, 22-Lower drive shaft (540 rpm), 23-Gear, 24-Snap ring, 25-Seal rings, 26-Bushing, 27-Needle bearing, 28-Sleeve, 29-Roller bearing, 30-Idler gear, 31-Clutch cup, 32-Piston, 30-O ring (inner), 34-"O" ring (outer), 35-Brake ring, 36-Piston back plate, 37-Friction disc, 38-Drive plates, 39-Return springs, 40-Clutch back plate, 41-Snap ring, 42-Thrust washer, 43-Clutch hub, 44-Snap ring, 45-Needle bearing, 46-Shaft safety cover, 47-Bearing seal retainer, 48-Gasket, 49-Oil seal, 50-Snap ring, 51-Ball bearing, 52-1000 rpm shaft

To disassemble the pto clutch, first use a pair of "C" clamps or a suitable puller and compress the return springs (39), then remove snap ring (41). Remove clamps or puller and remove clutch back plate (40) and return springs (39).

Remove friction discs (37), drive plates (38), piston back plate (36) and brake ring (35). Remove snap ring (44), thrust washer (42) and clutch hub (43). Bump front of clutch cup (31) on bench top and remove piston (32) with "O" rings (33 and 34).

Case IH Tractor Standard duty pto clutch has five friction discs and eight drive plates (two drive plates between each friction disc). Heavy duty pto clutch has six friction discs and five drive plates (one between each friction disc).

Clean and inspect all parts and renew any showing excessive wear or other damage. Pay particular attention to the clutch friction discs and drive plates which should be free of scoring or warpage. Use all new "0" rings, seals and gaskets during reassembly.

Bushing (26) for the 1000 rpm output shaft (52) or lower drive shaft (22) on 540 rpm unit is in the front of differential compartment. This bushing should be renewed if new shaft (52) or (22) is required or if seal rings (25) have grooved the bushing.

When installing bushing (26) bottom it in bore. Position needle bearing (27) to within 1/32-3/32 inch (0.79-2.38 mm) of front face of bushing (26).

Unlock and remove seal rings (25). Remove snap rings (24) and (20) or (50), then press bearing (21) or (51) off rear of shaft (22) or (52) and press gear (23) off front of shaft. Check to see that oil holes are clear and that roll pin is tightly in position in shaft. Use new seal rings and snap rings during assembly.

Inspect sleeve (28), roller bearing (29) and idler gear (17), if so equipped, and renew as necessary. Sleeve has a slot which must be aligned with pin in shaft (22) or (52) during assembly. Reassemble and reinstall PTO by reversing disassembly and removal procedures.

To remove the 540 rpm output shaft (8), gear (9), idler shaft (15) and idler gear (17), first remove hydraulic lift assembly. Remove snap ring (10) and unbolt bearing and seal retainer (2).

Withdraw output shaft assembly and remove gear (9) through top opening. Install a cap screw in rear of idler shaft (15), pull idler shaft from rear of frame and remove idler gear (17) from above. Use new' 'O'' ring (14), oil seal and gasket and reinstall by reversing the removal procedure.