Assisted brake master cylinders


The brake master cylinders are attached to the pedal console and are housed to the right of the cab front bulkhead. They act on the tractor main brake located in the centre housing. Depending on user requirements, the master cylinders can be activated separately or together in locked mode via a pedal latch (1)The brake master cylinder specifications are similar whether the requested option includes trailer brake or not. However, if the trailer brake option has been selected, an FTE valve (14) is added to the system to perform this function. This valve controls a second valve located in the external priority block of the hydraulic unit with two priority blocks. A quick coupling at the rear of the tractor provides the hydraulic link between the tractor and the trailer.


Legend 
1.Brake master cylinders without oil tank
2.Brake master cylinders with oil tank


The accumulator (1) fitted upstream of the brake master cylinders (5) is supplied by the low pressure system (17 or 21 bar). It quickens the response of the brake assistance mechanism. It also maintains the pressure in the brake master cylinders via the non-return valve (2) through the line (4) when the engine has been stopped.

Specifications


(1) Braking assistance accumulator
- Brand................................ Olaer
- Type ................................. 1/20
- Capacity ........................... 1 
- Gas................................... Nitrogen
- Tyre pressure................... 9 ± 1 bar

(2) Non-return valve
- Brand................................ Parker

When reinstall the non-return valve, turn the arrow engraved on its body so that it points in the direction of fluid flow.

(3) Main accumulator for:
- the Dynashift (GBA10 gearbox)
- the Powershift (GBA15 and GBA25 gearboxes)
- ranges 1 to 4 of gearboxes GBA15 and GBA25 (4) To brake hydraulic assistance

GPA20, GPA30 and GPA40 rear axle development and assemblies

GPA40 with old generation centre housing


 GPA40 with new generation centre housing



Parts list 
(1) Bleed screw
(3) Main brake supply lines (right and left)
(5) Brake master cylinders
(10) Connection to assist bleeding under pressure
(13) 17/21 bar low pressure supply line


 GPA20, GPA30 and GPA40 rear axles development and assemblies

GPA40 with old generation centre housing


GPA40 with new generation centre housing



Parts list 
(1) Bleed screw (3) Main brake supply lines (right and left) (5) Brake master cylinders (6) Oil reserve (7) Trailer brake quick coupling (10) Connection to assist bleeding under pressure (13) 17/21 bar low pressure supply line (14) FTE valve (trailer brake) (15) Trailer brake control line
(16) Priority blocks with trailer brake (hydraulic unit with two priority blocks)




After replacing the brake master cylinders and/or FTE valve:
- Bleed the main brake system and trailer brake system (if fitted).
- If necessary, check for slight operating clearance between the brake pedal control rods and their respective brake master cylinder.
- Also check the operation of the locking latch.