GPA30 rear axle PTO - Operation


The PTO housing fitted to the rear of the tractor rear axle contains all mechanical GPA30 power take-off components:
- Certain components rest on taper roller bearings whose cups are free fitted or force fitted onto the PTO housing or clutch unit;
- the front end of the output shaft rests on a cylindrical roller bearing.
Power take-off is independent of the transmission.

Description and operation of the different rear PTO versions

There are three versions:
A - long or short interchangeable output shaft, 540/1000 rpm as a standard, or 750/1000 rpm as an option.
B - jaw coupler - long or short flange shaft, 540/1000 rpm as a standard, or 750/1000 rpm as an option.
C - fixed coupler  - 1000 rpm flange shaft.

Version A 

2 speed power take-off long or short interchangeable output shaft (13), 540/1000 rpm or 750/1000 rpm (depending on version).

Operation
The clutch unit assembly (15) is splined to the double driving pinion (11). This pinion is constantly meshed with the 540/1000 rpm (7) (18) or 750/1000 rpm (7) (18) driven pinions (depending on version) of the lower shaftline. The output speed of the rear PTO is achieved by replacing the interchangeable output shaft (13) only.

Parts list 
(7) 540 or 750 rpm driven pinion (11) Double driving pinion (13) Output shaft (15) Clutch unit assembly (18) 1000 rpm driven pinion

Version B 

2 speed power take-off
- Jaw coupler (10) controlled by a cable from the driver’s seat, or directly by an external control
- Output shaft (13)
- long or short flange shaft (5) 540/1000 rpm or 750/1000 rpm (depending on version)

Operation
The clutch unit assembly (15) is splined to the driving pinions (9) (11). These pinions are constantly meshed with the 540/1000 rpm (7) (18) or 750/1000 rpm (7) (18) driven pinions (depending on version) of the lower shaftline. The rear PTO output speed is achieved when the jaw coupler (10) is shifted either forward 540 or 750 rpm, or backward 1000 rpm.

Parts list 
(5) Flange shaft (7) 540 or 750 rpm driven pinion (9) 540 or 750 rpm driving pinion (10) Jaw coupler (11) 1000 rpm driving pinion (13) Output shaft (15) Clutch unit assembly (18) 1000 rpm driven pinion

Version C 

1000 rpm power take-off
- Fixed coupler (10)
- Output shaft (13)
- 1000 rpm flange shaft (5)

Operation
The clutch unit assembly (15) is splined to the driving pinion (11). This pinion is constantly meshed to the driven pinion (18) of the lower shaftline and drives the output shaft (13) of the rear PTO. On version C, a spacer (19) replaces the 540 or 750 rpm driving pinion (9). The fixed coupler (10) is coupled to the driven pinion (18) (1000 rpm). It is immobilised by a snap ring (1) clipped to the hub (20), itself immobilised by a snap ring (26) clipped onto the output shaft (13).

Parts list 
(1) Snap ring (5) Flange shaft (10) Fixed coupler (11) 1000 rpm driving pinion (13) Output shaft (15) Clutch unit assembly (18) 1000 rpm driven pinion (19) Spacer (20) Hub (26) Snap ring

Operation of the upper shaftline
The upper shaftline of the rear PTO transmits engine speed to the driving pinion through:
- a clutch;
- a series of three shafts: mainshaft, primary shaft and secondary shaft.

Clutch
The clutch assembly (15) is fed by the low pressure (17 bar) hydraulic circuit and via push buttons inside
the cab (PTO engaged position). 


It is located on the upper shaftline and in front of the driving pinions. It is supported by two taper roller bearings mounted opposite in a unit attached to the PTO housing:
- the front clutch bearing cone is force fitted onto:
- the clutch unit (PTO version A),
- the driving pinion (9) (540 or 750 rpm, PTO version B),
- the spacer (19) (PTO version C);
- the rear clutch bearing cone is free fitted onto all PTO versions;
- the taper roller bearings are adjusted with clearance using (a) shim(s) inserted between the driving pinion cover and unit.

Power take-off brake
When the clutch is disengaged and the control button in the cab is placed in the "PTO brake" position, the 17 bar pressure acts upon a piston (1), which in turn presses against the unit (6), progressively braking the rotation of the PTO mechanical components. 


Lubrication of the clutch assembly shaft A central channel with radial ports respectively provide:
- pressurised lubrication of the clutch discs and intermediate plates;
- pressurised lubrication of the driving pinion(s) (depending on version) of the clutch assembly shaft.

Lower shaftline
The lower PTO shaftline consists of:
- a unit and a cylindrical roller bearing fitted at the rear of the centre housing (version A);
- a cylindrical roller bearing directly force fitted onto the centre housing and preceded by an oil deflector (versions B and C);
- a rear bearing block consisting of two taper roller bearings fitted:
- on a sleeve integral with the rotating PTO output shaft (version A),
- directly onto the PTO output shaft (versions B and C);
- a cassette seal providing PTO lower shaftline output shaft tightness;
- an output shaft (interchangeable shaft, version A, or flange shaft, versions B and C). The output shafts may be of different lengths and fitted with 6, 20 or 21 splines, depending on the type and rotational speed tolerated by the implement. 


Lubrication of the lower shaftline A central channel with radial ports provides splash lubrication of:
- the driven pinions and bearings (PTO versions A and B);
- the bearings (PTO version C).