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Massey Ferguson 8280 gearbox - Input unit with power shuttle

MF 8100-8200 Series Tractors Repair Operations

The power unit with power shuttle is in the form of an interchangeable module on which a reverse shuttle is assembled that can power the forward or reverse gear.

It is made of two distinct parts: the power shuttle and the Dynashift.

Dynashift

The MF 8280 gearbox dynashift electro-hydraulically controls four powershift ratios using a lever mounted to the left under the steering wheel. It is located between the power shuttle and the driving gear mounted in the rear housing.

The Dynashift function is performed by two epicyclic gear trains associated with two hydraulic clutches. For information on operation.

A removable flange (2) supports the front end of the selector rails (Fig.21).
This assembly enables easy horizontal removal of the input unit (Fig.22).

Uncouple the Massey Ferguson 8280 tractor between the engine and the gearbox.

Drain the gearbox. Remove the selector cover and through the opening, over the gearbox, remove the screw (1) attaching the flange (2) (Fig.21).

Move the flange away from the housing by making it slide along the selector rails.

The flange (2) is positioned on the rear housing of the input unit by means of two cotter pins (3) (Fig.23).

Remove the clutch cover plate.
Remove the power shuttle control unit.

Remove and mark the position of the hydraulic pipes connected to the following functions:

- gearbox lubrication
- Dynashift low pressure
- power shuttle rear clutch low pressure

Remove the power shuttle front clutch.
Take out the PTO shaft (1) from the MF 8280 gearbox (Fig.22) and mark its position.
Disconnect and remove the progressive sensor located above the gearbox.
Sling the input unit using tool , a locally made handling bar and a lifting device adapted as per Fig.22.

Before using the sling, remove the four screws (64) (L = 145 mm) unless removed beforehand they will not be accessible to the "U" profile of the tool.

Remove the remaining screws (64A) (L = 145 mm) securing the input unit to the gearbox (Fig.24).
Do not intervene on the short screws (70) (L = 25 mm) so as to avoid splitting the unit.

With the help of an assistant, carefully pull the unit forward and disengage it from the gearbox to proceed with removal.

Remove the handling bar and tool. Place the unit in vertical position on a workbench. Separate the rear clutch from the input unit.

Refitting

Install the previously removed rear clutch on the input unit. If necessary, screw a guide stud (L = 55 mm) on the gearbox housing, through the opening revealed by the removal of the power shuttle control unit.

Place the locating pin (1). Check presence of the flange (2), lubrication tube (4) (Fig.25) and the locating pins (3) (Fig.23).

With the help of an assistant and using the tools used during removal, position the input unit in the gearbox housing taking the same safety precautions as previously.

Push and position the input unit on the housing mating face. Remove the guide stud (if used). Remove the sling. Tighten the screws (64) (64A) (Fig.24) of the input unit to a torque of 47 - 57 Nm.

The thread of each screw should be cleaned and lightly coated with Loctite 542 or equivalent. If new screws are used, they should not be coated with Loctite or equivalent since they are coated with a locking product in the factory.

Install and adjust the progressive sensor. Adjust the turned section of the PTO shaft to the rear and insert the shaft into the upper shaft line of the Massey Ferguson 8280 gearbox. Install the front clutch.

Adjusting of the progressive sensor

Lightly coat the sensor with Loctite 577 (Sensor Sealing or equivalent). Install and adjust the sensor. Fully screw home the sensor without forcing.

Make sure that its end is in contact with the driving pinion mounted in the rear housing. Unscrew the sensor by approximately a half or threequarter turn, then torque the nut to a value of 5 to 7 Nm.

Install the power shuttle control unit and the hydraulic pipes according to the positions previously marked. Install the clutch cover plate.

Check presence of the locating pins (3) and apply the flange (2) to the rear part of the housing (Fig.23). Clean screw thread (1) and apply a light coating of Loctite 221 or equivalent and torque to 36 - 46 Nm.

Install the selector cover. Top up housings with oil and check the level on the sight-glass on left at rear of central housing. Couple the tractor between the engine and the gearbox.

Carry out a road test with the power shuttle, testing gears A, B, C, D of the Dynashift. Check the oil tightness of the selector cover mating face and of hydraulic unions.