Tandem Master Cylinder (THV) (Skoda Octavia 1U)

Working diameter of the main tandem brake cylinder (further only THV) is 23.81 mm, it is made in the form of a double ring and is installed in a horizontal position. A brake fluid reservoir, which is mounted directly on the cylinder with rubber bushings and attached to it, is also a part of the THV mounting kit.

The THV creates excess pressure for the foot brake system. It is controlled by the brake pedal using a vacuum brake booster. The THV housing is cast iron and is attached to the booster via a flange with two nuts. The bosses with M12 x 1 thread are used to connect the tubes leading to the individual brake cylinders in the wheels. On one side (right in the direction of travel) there are terminals for the front wheel brakes, and on the opposite side there are terminals for the rear wheel brakes.

The THV has a spool valve system for bypassing brake fluid between the working volumes of the cylinder and the brake fluid reservoir.

Tandem brake cylinder is used for non-ABS brake system, similar one is used with built-in ABS system (or ABS/EDS).

Since the manufacturer prohibits any independent intervention in any unit of the brake system, details of the design and dismantling of the THV are not provided here. In case of malfunction, contact the Skoda service. We will add that if the function of one brake circuit is disrupted, this also means if the front or rear part of the THV fails, the second circuit remains in working order and the car retains approximately 50% of its braking capacity.

Of course, in this case the pedal stroke will be extended by about the same 50%. The remaining circuit ensures safe braking of the car.