Ground Speed PTO GPA40 - Remove and reinstall

GSPTO is an abbreviation of "ground speed power take-off". It may be available (depending on option) on certain types of tractors fitted with GTA1040 or GTA1540 transmission (40 kph only). In contrast to the independent PTO mechanism where the speed of the rear PTO output shaft depends on the speed of the engine, the GSPTO is driven by the pinion and a set of gears also used by the 4WD clutch unit. The speed of the rear PTO output shaft is therefore proportional to the tractor's travel speed.

The pinion of the rear crownwheel and pinion supports the driving gear (17), which is constantly meshed with the bell gear (33) of the 4WD clutch unit. On the ground speed PTO, the gear (27) is constantly meshed with the driven gear (10), which is attached to the 540 rpm driven gear (7) by the screw (12). This gear is itself splined to the output shaft (13) of the rear PTO.

The forward movement of the coupler (31) allows the movement transmitted by the gears (17) (33) to travel towards the output shaft (13) of the rear PTO via the shaft (8) and the gears (27) (10). The coupling is activated by an external rod located at the bottom right of the rear PTO housing. This rod is connected to a cable, which is connected to a control lever accessible from the cab. A switch connected to this control lever electronically controls the engagement of the ground speed PTO. When the GSPTO is engaged, the independent 540 - 1000 rpm PTO is deactivated.

Parts list 
(1) Fork (2) Selector rail (3) Circlip (4) Snap ring (5) Control pin/finger (6) Splined sleeve (7) 540 rpm driven gear (8) Shaft (9) Pinion (10) Driven gear (11) Bearing cone (12) Screw (13) Output shaft (14) "O" ring (15) Pushrod screw (16) Nut (17) Driving gear (4WD) (18) Bearing cone (19) Bearing cup (20) Shim(s) (21) Countersunk screw (22) Chamfered washer (23) Ball bearing (24) Circlip (25) Nut (26) Sleeve (27) Driving gear/shaft assembly (28) Set screw (29) Hub (30) Bearing cup (31) Coupler (32) 4WD shaft (33) Bell gear (4WD)

A Details
B Details
S Removable support
GTA1040 version
GTA1540 version

Removing and install the selection mechanism and adjusting the pushrod screw

Disconnect the PTO housing from the centre housing.

Removing the selection mechanism
Remove rod B.
Remove the snap ring (4).
Separate the control pin/finger (5) from the selector rail (2). Turn it approx. 90° and pull it out of the PTO housing in order to remove the "O" ring (14).
Remove the control pin/finger (5) by pushing it along its entire length towards the inside of the PTO housing.
Unscrew the nut (16) and the pushrod screw (15) on the selector rail (2).
Unscrew the set screw (28). Remove the selector rail (2) and the fork (1).

Install the selection mechanism
Clean and check all components. Replace those that are defective.
Install the fork and the selector rail.
Lightly smear the thread of the set screw (28) with Loctite 221 or equivalent. Tighten this screw to a torque of 25-35 Nm.
From the inside of the PTO housing, Install the control pin/finger (5) in its position and press it fully back towards the outside of the housing. Lubricate a new "O" ring (14). From the outside of the PTO housing, Install the new "O" ring (14) in the groove of the protruding section of the control pin/finger. Push the control pin/finger assembly back inside the PTO housing. Position it in the slot on the selector rail (2).
Reinstall :
- a new snap ring (4);
- control rod B.
Lightly smear the thread of the screw on control rod B with Loctite 221 or equivalent. Tighten this screw to a torque of 25-35 Nm.
Check the movement of rod B.

Adjusting the pushrod screw (15)
Position the selector rail (2) so that its flat section is opposite the tapped hole of the pushrod screw (15).
Tighten the pushrod screw (15) without forcing it in order to compress the ball, then loosen it by one quarter turn.
Clean the thread of the pushrod screw (15) and the nut (16).
Lightly smear the thread of the nut (16) with Loctite 242 or equivalent. Tighten this nut to 15-20 Nm while holding the pushrod screw in place.
Check that the fork lock matches.
Reconnect the PTO housing to the centre housing.
Start the tractor engine and check the ground speed PTO operation.