If the brake pedal is hard to push up and down this could be a sign of a faulty servo unit. This unit is part of the brake master cylinder, which connects to the brake pedal using pushrods and is typically positioned on the nearside of the engine compartment.
The servo unit is used in a hydraulic braking system to reduce the pressure required by the driver when applying the brakes. It works by using the power of a vacuum created by the suction of the intake manifold in the internal combustion engine. This reduces the amount of driver effort required when braking. The remaining power is then transferred to the master cylinder.
If a servo unit or the brake master cylinder is damaged, this could lead to complete failure of a vehicle’s hydraulic braking system. This may be evidenced by a hydraulic fluid leak, or the brake pedal being flat to the floor. If just the servo unit fails, the driver will notice an increased difficulty in depressing the brakes. As with all brake issues, it is very important that they are addressed quickly to prevent any further damage to the vehicle.