Hydraulic system – Load Sending Left-hand cover plate


With the exception of the profile of certain hydraulic components, the design and operation of the left-hand cover plate are virtually identical for tractors equipped with 110 l/min Load Sensing hydraulic equipment (GPA20, GPA30 or GPA40 rear axles) or 150 l/min Load Sensing (LS) hydraulic equipment (GPA40).

Tractors equipped with a GPA20 or GPA40 rear axle

The left-hand cover plate (14) is Installed on the centre housing.


It supports:
on the internal face:
- the charge pump (2) with a capacity of 60 cm3/revolution, 71 cm3/revolution or 80 cm3/revolution (according to specification) (GPA20 and GPA40 rear axles) (110 l/min LS hydraulic system) or the charge pump (2) with a capacity of 100 cm3/revolution (GPA40 rear axles) (150 l/min LS hydraulic system)


Parts list 
(1) Continuity pipe (2) Charge pump (3) Charge pipe (4) Suction manifold (suction and resupply) (5) "O" ring (6) 150 μ suction strainer (7) Studs (8) Plug (9) Seal (10) Screw (11) Washer (12) Gear (13) Key (14) Left-hand cover plate (15) Nut (16) Locating pins (17) "O" ring (18) Flat seal (19) Screw
(20) Strainer bowl (21) "O" ring (22) Screw (23) "O" ring (24) Dowels 
(26) "O" ring (27) Suction pipe (28) Nuts


- the drive gear (12) fitted on the charge pump
- the suction manifold (4);

on the external face:
- the 150 micron suction strainer (6).

The engine movement transmitted to the gear (1) via the shaft (5) drives the gear (12) for the charge pump (2)


The oil is sucked in by the manifold (4). It is then directed to the strainer and the charge pump (2) via a channel moulded into the cover plate. The oil delivered by the charge pump (2) is directed to the variable displacement pump (41) via the charge pipe (3). When the high pressure hydraulic slave devices (e.g. auxiliary spool valves) are not activated, the charge pump (2) is resupplied via the 5 bar safety valve (44).


Parts list 
(1) Continuity pipe (2) Charge pump (3) Charge pipe (4) Suction manifold (suction and resupply) (41) Variable displacement pump (44) 5 bar safety valve

Legend
A Inlet port

Tractors equipped with a GPA30 rear axle

The left-hand cover plate (14) is Installed on the intermediate housing.
It supports:
on the internal face:
- the charge pump (2) with a capacity of 60 cm3/revolution (GPA30 rear axle)
- the drive gear (12) fitted on the charge pump
- the suction manifold (4);


on the external face:
- the 150 micron suction strainer (6).


Description 
The engine movement transmitted to the gear (1) via the shaft (5) drives the gear (12) for the charge pump (2). The oil is sucked in by the manifold (4). It is then directed to the strainer (6) and the charge pump (2) via a channel moulded into the cover plate. The oil delivered by the charge pump (2) is directed to the variable displacement pump (41) via the charge pipes (3) and (54). When the high pressure hydraulic slave devices (e.g. auxiliary spool valves) are not activated, the charge pump (2) is re-supplied via the 5 bar safety valve (44), the pipe (55) and the manifold (4).


Parts list 
(2) Charge pump (3) Charge pipe (4) Suction manifold (suction and resupply) (5) "O" ring (6) 150 μ suction strainer (17) "O" ring (25) "O" ring (26) Mecanindus pin (44) Safety valve (54) Charge pipe 
(55) Continuity pipe from 5 bar safety valve

Legend
C Partition integral to the intermediate housing


Parts list 
(2) Charge pump (3) Charge pipe (4) Suction manifold (suction and resupply) (5) "O" ring (6) 150 μ suction strainer (7) Studs (8) Plug (9) Seal (10) Screw (11) Washer (12) Gear (13) Key (14) Left-hand cover plate (15) Nut (16) Locating pins (17) "O" ring (18) Flat seal (19) Screw (20) 150 μ strainer bowl (21) "O" ring (22) Screw (23) "O" ring (24) Dowels (28) Nuts

Identification of channels and ports


on the cover plate 
A Suction port [oil from manifold (4) and continuity pipe (1) or (55) (depending on assembly)] C 150 μ suction strainer G Charge port [oil directed to variable displacement pump via the charge pipe (3) or the charge pipes (3) and (54) depending on assembly]