Pressure spring

Attention:

The bore for the piston return spring has not been machined deep enough.
If excessive, continued pressure is applied to the brake discs especially during road transport, premature wear may occur on the brake discs.
Check the depth of the hole (12.5 mm) that receives the piston return spring (part number 5120761). If the hole has been machined incorrectly, you will need to either drill out to the design depth of 12.5 mm or add spacers to get the correct depth.

The bore for the piston return spring has not been machined deep enough.
The hydraulic filter is inhibited with brake disc wear. Excessive prolonged pressure on the brake disc can cause the friction material to come off the disc.
If excessive, continued pressure is applied to the brake discs, especially during road transport, premature wear of the brake discs may occur.
When replacing worn brake discs it is recommended to check the following:
That the three holes housing the brake piston return springs are correct. If it is found that a hole is drilled incorrectly, either drill it further or add shims to obtain the correct design depth of 12.5 mm. The 12.5 mm should be measured from the machined brake surface from the disc.
That the three anti-rotation pins of the brake pistons protrude 9.5 mm from the machined surface from the rear axle housing.
The springs are designed to apply gentle pressure to the friction discs via the brake piston. This ensures that the brake pedal travel does not become too long. If the springs are not placed correctly, the brake pistons will be pushed back into the gearbox housing by the rotational movement of the friction discs. This would cause the pedal to almost reach the floor when the brake is first applied before any brake pedal resistance would be felt.

Notice:
Return springs 5120761 and pins are fitted to tractor models 120 - 155 only.
When replacing the brake discs, it is recommended that the latest Kevlar discs are used.

Install the latest brake discs with a Kevlar friction surface.
Loud braking noise (hitting, rattling, screeching or squealing).
Premature wear of the brake discs.
Heavy brake application and heat from the rear axle oil will destroy the adhesive in the brake disc friction material.
Type of brake material used tends to squeal on machines that are driven a lot on roads and therefore have higher rear axle oil temperatures.
Brake discs that have Kevlar friction surfaces are now available from the parts department.
The Kevlar brake discs have been introduced into production from the following serial number: -
TM 120 - 155 ACM199748 New Kevlar brake discs 47126359 (old 5154521 Organic)
TM 170 - 190 ACM198908 New Kevlar brake discs 47126358 (old 5199927 organic)