PTO driving pinions and Layshaft


On tractors the layshaft, clutch, bearings and driving pinion form the upper shaft line of the rear power take-off PTO. The upper shaft line passes through the intermediate and centre housings to then transmit the engine speed to the driving pinions located in the rear housing. The layshaft is supported at the front by a bearing block mounted on two ball bearings housed in the bore of the intermediate housing and at the rear by the clutch assembly (15) in which the driving pinions are integral via splines.


1

Parts list 
(1) Circlip (2) Bearing cone (3) Bearing cup (4) Cover (5) Shims (6) Unit housing (7) Bearing cone
(8) Bearing cup (9) Driving pinion (10) Spacer (11) Driving pinion(s) (12) Circlip (27) Bolt (28) Layshaft



2

On unit (23), the cups (3) (8) are free mounted in their respective bores. The bearing cone (7) is mounted free on the splined part of the clutch. Depending on the type of power take-off, the bearing cone (2) is force fitted on:
- the clutch unit (15)
- the pinion (9)
- the spacer (10)

Identification of the assemblies corresponding to the types of power take-off PTO available
"a" : removable shaft
"b" : jaw coupler
"c" : 1000 rpm
Remark
- Uncouple the power take-off PTO housing from the centre housing to carry out maintenance on the following components:
- driving pinion(s)
- unit housing (6)
- cover (4)
- bearings (2) (3) and (7) (8)

Removing and installing the driving pinion, bearings and layshaft


Special points (Fig.1)
- If the layshaft (28) mounted on tractors fitted with Powershift transmission has to be replaced, it is absolutely necessary to remove the left-hand side hydraulic cover to gain access to circlip (1), since this will not pass through the hole provided in the wall of the intermediate housing. Before removing the shaft, visually note its profile in order to later pass the crownwheel of the bevel gear through.
- On tractors fitted with Heavy Duty transmission, the layshaft does not has a circlip (1).

Removal
Remove and separate the clutch (15) and unit (23) assembly.
Assembly PTO type "a" (Fig.2-3)


3

Extract bearing cone (2) from the clutch unit and remove it. Take off bolts (27), cover (4) and shim(s) (5).
Take out the driving pinion (11) from unit (6).
Disassemble the cups (3) (8) (as required).
Assembly PTO type "b" (Fig.2-4)


4

Remove pinion (9) and bearing cone (2). Take out cup (3) from the cover (4).
Remove the cover and shim(s) (5).
Take out cup (8) from unit (6). Extract cone (2) (as required).
Assembly PTO type "c" (Fig.2)
- On this type of assembly, the method is similar to that used for assembly "b" type.

Refitting
- If maintenance has been carried out on one of the components stated at the beginning of this section, it is important to carry out shimming of the bearings (2) (3) and (7) (8).
Assembly PTO "a"
If disassembled, place cups (3) and (8) in cover (4) and unit (6) respectively.
Install the driving pinion (11), the shim(s) (5) (if adjustment is not necessary), the cover (4) and the bolts (27) on unit (6).
Using a press and an appropriate fixture, insert bearing cone (2) into the clutch housing.

Assembly PTO "b"
If disassembled, place cups (3) and (8) in cover (4) and unit (6) respectively.
Position pinion (11) in unit (6), the long offset "D" turned to face cover (4) (Fig.1-4).
Install the shim(s) (5) (if adjustment is not necessary), the cover (4) and bolts (27) on unit (6).
Using a press and an appropriate fixture, insert bearing cone (2) in pinion (9).
Assembly PTO "c"
- In this type of assembly, assemble the components using the assembly principle used in the “b” type
assembly.
Reassemble and refit clutch (15) and unit (23) assembly.

Shimming
Assemble clutch (15) with unit (23).


5

Fasten the cover (4) and the unit housing (6) with four bolts (27) and nuts (14) that should be supplied locally (Figs. 5 - 6). Hold the assembly (23) in a vice fitted with soft jaws (Fig. 5).





Place the index of a dial gauge on the end of the sleeve (10).
Pull hard on the clutch unit while turning it alternatively left and right in order to correctly seat the cones in the cups.
Reset the dial gauge to zero.

Pull hard on the clutch unit while turning it alternatively left and right in order to correctly seat the cones in the cups, but this time by pushing.
According to the provisional clearance measured on the dial gauge, determine a new thickness of shim(s) (5) to obtain a definitive clearance (Fig.6): J1 = 0 to 0.10 mm.