Gearbox with Power Shuttle - Selector cover


Tractors fitted with a gearbox and power shuttle have a selector cover that features a single control lever.
This lever selects the four basic gears as well as the hydraulic Hare / Tortoise (Hi-Lo) function. The gear lever (2) is controlled by a single linkage and cable (Fig.3) and is located on the right above the console.

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When the tractor is stopped with the handbrake on, a "C" cell fixed onto the selector cover by means of a bracket (Fig.3) informs the user that a gear is still engaged and that the handbrake is on. This information is issued by a buzzer located under the instrument panel surround.

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Parts list
(1) Return port (2) Grounding lug (3) Screw (4) Temperature probe and seal (5) Plug (6) hose pipes holding lug (7) Selector cover (9) Finger and pin assembly (gears) (10) Grid (11) Screw (12) Spring (13) Cup (14) Cup (15) Spring (16) Cup (17) Seal (18) Shouldered ring (19) Seal(s) (20) Hare / Tortoise switch

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The gear lever
Selecting 1st and 2nd gear ratios
- The gear lever (2) pushes lever "L" (Fig.3) and engages the finger (9) in the 1st and 2nd gear fork (Fig.1).
- The first gear ratio is obtained by moving lever "L" upwards, and second gear by moving it downwards.
Selecting 3rd and 4th gear ratios
- In this configuration, the gear lever (2) (Fig.3) is in the intermediate position. The finger (9) integral with pin "A" engages in the fork of the 3rd and 4th gear ratios (Fig.1).
- Third gear is obtained by moving lever "L" upwards, and the fourth gear by moving it downwards.
Safety interlock
- A locking system located on the rear face of the gearbox, at the end of the selector rails, prohibits any accidental gear shifting.

Hare / Tortoise function
Identification of components (Fig.4)

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(1) Solenoid valve (2) O’ring (3) Piston (4) Bearing (5) O’rings (6) Circlip (7) Selector cover

Selecting the Hare / Tortoise range is carried out with the gear lever in neutral position, by pulling lever "L" towards the outside of the cover (Fig.3). The finger (9) presses the end of switch (20) (Fig.1) which informs the electronic system that the Hare / Tortoise valve is available and can be switched.

The Hare position (Fig.4)
The solenoid valve (1) mounted on the selector cover (7) is closed and causes a drop in pressure in chamber "B". The constant pressure (17 bar) in chamber "A" thrusts on the annular face of piston (3) which moves forward and pushes the fork "F1" to the Hare position via the selector "S". The oil contained in chamber "B" returns to the housing via the solenoid valve.

The Tortoise position (Fig.4)
A fresh operation of the switch (20) (Fig.1) causes the opening of solenoid valve (1) (Fig.4). The 17-bar pressure enters chamber "B". The pressure acting on the larger piston diameter is higher than that on the annular face of the piston and forces it to return, moving selector "S" and fork "F1" into the Tortoise position. The oil contained in chamber "A" returns to the 17 bar circuit.

Safety interlock
The Hare / Tortoise selector rail is similarly locked in each of its positions (Hare or Tortoise) in the 1st to 4th gear ratios, by the same previously described system.

Removing and refitting the cover


Immobilise the tractor. Chock the rear left wheel. Put on the handbrake.
Place wedges for safety between the frame and the front axle.
Remove the rear right wheel or set it to wide track position. Install an axle stand if necessary.
Pivot the footstep and battery chest assembly or remove the neighbouring elements that may hinder the removal of the selector cover (depending on the version). Drain the gearbox.
Disconnect the electrical connectors on the cover.
Unscrew or loosen the pipes and hoses on the cover.

Gear shift control 
Disconnect the harness from cell "C" (Fig.3). Remove the ball joint (4). Remove screws (3).
Remove pins (11). Remove the ball joint (5).
Note the adjustment of the cable (6). Slightly loosen the top nut (12) and separate the cable from bracket (2).
Remove screws (3), mark the location of the grounding lug (2) and the the hose pipe clamp (6) (Fig.1).
- On tractors fitted with a creeper unit, disconnect the control cable (1) and remove bracket (2).
Loosen and remove the selector cover.
Clean the mating faces of the gearbox and the cover.

Install :
On the cover: the Hare / Tortoise piston in the Hare position.
On the gearbox: the Hare / Tortoise fork in the Hare position, the 1st, 2nd, 3rd, and 4th forks in the neutral position.
Lightly smear the housing /gearbox mating face with Master Loctite 510 or equivalent.
Turn the gear shift control linkage on the cover so that it fits into selectors "S" when positioning the cover on the gearbox.
If necessary, refit the creeper unit cable bracket. Reconnect and adjust the control.
Install the bracket (2). Fit and tighten up the screws (3) to a torque of 34 - 70 Nm.
Install the gear shift control.
Using a grease gun, grease the various linkages of the gear shift control on the selector cover.
As necessary, refit those components removed previously from around the cover.
Install the wheel and tighten the wheel nuts or studs to the correct torque depending on the version.
Top up the housing oil level and check it with the sight glass located at the rear of the centre housing.
Remove the wedges from between the frame and the front axle. Release the handbrake.
With the engine running, check the gear shifting of all gears and Hare / Tortoise positions.
Stop the engine and where necessary adjust the gear shift control.
Check that the buzzer of the safety cell vibrates correctly (ignition on, handbrake on and gear engaged).
Carry out a road test.

Replacing Hare / Tortoise piston seals (Fig.4)
Remove the cover.
Take off circlip (6). Extract piston (3) with the bearing (4) and discard the O’rings (2) (5).
Clean and check the parts. Replace any defective components.
Without fitting O’rings on the piston, check that the piston slides smoothly in the bore of the cover.
The above check completed, lubricate and fit new O’rings. Carry out operation 30 in reverse order.
Install the selector cover.
- The replacement of piston (3), bearing (4) or circlip (6) requires the checking and readjustment of selector "S" of the Hare / Tortoise range.

Disassembling and reassembling the selector mechanisms


Remove the cover and hold it in a vice with jaw protectors.
Remove the screws (1) (4). Take off the selector (3), and bracket (2).
Remove screw (11).
Remove the gear shift control assembly.
Remove the spring cups (14) (16) and spring (15).
Separate the finger and pin assembly (9) from the grid (10). Remove spring cup (13) and spring (12).
If necessary, unscrew and remove the Hare/Tortoise switch (20), the unions screwed on the return ports (1) and the temperature probe (4). Recover the seal(s) (19) from the Hare/Tortoise switch.
Extract the seal (17).

Special point
If the guide ring (18) has to be replaced, coat its rim lightly with Loctite 638 or its equivalent and insert it in thrust against the shoulder of the cover.
If removed, refit the Hare/Tortoise switch (20) with the same number of seals as removed, and with the unions on the return ports, and the temperature probe lightly smeared with Loctite 542 or its equivalent.
Lightly smear the external diameter of seal (17) with Loctite 542 or its equivalent and insert it into the cover using a suitable tool.
Install spring (12) and cup (13) on pin (9).
Assemble pin and grid (10).
Refit cups (14) (16) seperated by spring (15).
Install the pin (9) and finger assembly without damaging the lip of seal (17). Fit and tighten screw (11) to a torque of 25 - 35 Nm, the thread previously lightly smeared with Loctite 270, or equivalent.

Positioning bracket (2) (Fig.5)

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Install bracket (2), ensuring a clearance of 29 mm between the bracket and the 22 mm diameter of pin "A" (Fig.5). Lightly smear the screws (1) with Loctite 270 or equivalent, and tighten them to a torque of 25 - 35 Nm.
This clearance must be complied with in order to ensure the correct operation of the cell.
Install the link (3) and tighten screw (4) to a torque of 30 - 35 Nm, the threads previously smeared with Loctite 241, or equivalent.
Check that the selector mechanism moves freely without constraint. Remove the cover from the vice and refit it on the gearbox.

Fitting and adjusting the gear Linkage


Gear linkage (cab side)
On the end of control linkage (1), shaped with an angle of 166°, turn the ball joint (2) as shown in the figure. Tighten nut (3).
Screw the ball joint (4) to thrust against the cable (6). Tighten nut (5).
Fit bracket (7) on a bench.
Onto this bracket, fit and tighten the following components:
- the gear lever
- the previously prepared control linkage and cable.
Install and secure the bracket on the right wheel housing in the cab. During this operation, ensure the control linkage and cable are inserted through the openings in the bulkheads. Fit the grommets.

Gear linkage (selector cover end)

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(Fig.6) Screw the threaded rod (9) (complete with nuts (3) and the ball joint (4) onto link rod (1).
Tighten ball joint (5) in thrust against cable (6). Tighten nut (7).
Tighten and lock the other end of the ball joint (5) onto cam (8).
On bracket (2), and with lever "L" fitted beforehand, position cam (8) and its extension piece (10). Fit pins (11), and lock them in place with new cotter pins.
Install the ball joint (4) on lever "L". Position the washer, and tighten the locknut.

Adjusting the link rod (1) (Fig.6)
Rotate threaded rod (9) and the ball joint (4) so as to obtain a distance "X" of 11 mm ± 1 mm between the two nuts (3) when these are tightened.

Adjusting the cable (6) (Fig.6)
Adjust the end-point of the sheath so as to balance dimensions "C" and "D". Tighten nuts (12) without
altering the adjustment.
Check for the proper engagement of each gear ratio and the position of the gear lever in the opening of the console.
This check should be performed with the dust cover of the gear lever temporarily removed.

Engage each gear, and select the Hare/Tortoise range. During this operation, check that the lever does not come closer than 5 mm to the edge of the console.
When there is no interference with the operation of the lever by the console, then the adjustment is correct. Refit the dust cover. If the position of the lever is incorrect, repeat the adjustment procedure at the selector cover end.
- if there is interference when engaging 1st or 3rd gears, reduce dimension "X" (Fig.6)
- if there is interference when engaging 2nd or 4th gears, increase dimension "X" (Fig.6)
- by altering dimensions "C" and "D" (Fig.6), the gear lever moves in the console.

Adjusting the Hare / Tortoise range
On the cover (7) (Fig.7)

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Place piston (3) in thrust against the bottom of the chamber (Hare position).
Position the arm of tool, in the groove of the piston and place it in contact with face "F" as shown. Hold piston (3) thrust against face “F” before tightening the thumbscrew “V” of the cursor.

On the gearbox (Fig.8)
Place the tool on the gearbox housing.

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Manually hold the ring of the synchromesh against the pinion of 3rd "P" (Hare position) (Fig.4) and with the forkpads thrust against the synchromesh ring (on the side of the 3rd gear pinion).
Smear the screws of selector "S" with Loctite 221 or equivalent and adjust them so that face "F" clears the arm of the tool by a minimum of 0.2 mm.
Temporarily refit the cover. Use a compressed air supply sufficient to move piston (3) into the Tortoise position.
Adjust and maintain the pressure to approximately 3 bar. Through the opening located beneath the gearbox, check the clearance between the Hare / Tortoise fork and the synchromesh ring. The clearance should be 1 mm maximum.
After verifying the clearance, take off the selector cover and definitively tighten the screws of selector "S" to a torque of 35 Nm without modifying the adjustment. Definitively refit the cover.