This invention relates to a fluid reservoir made of a resin material for a tandem master cylinder and, particularly to an improvement of a fluid reservoir for a tandem master cylinder provided in a vehicle.
It has recently been proposed that in order to reduce the weight of a vehicle brake master cylinder assembly the reservoir portion thereof is made of a synthetic resin material, such as polypropylene or polyamide, and secured to a master cylinder body made of a metallic material, such as aluminium or iron.
However, ordinary resin material is deformed by heat. If the above-mentioned proposal is adopted, therefore, the resin reservoir will be affected by for example heat emitted from the engine and expand at a high rate thereby causing a large deformation of the reservoir by the temperature of the surrounding cylinder and since the reservoir and the cylinder body have different thermal coefficients of heat, the fluid tight connection may be damaged, thus obstructing brake operation. Particularly, in case of the reservoir for the tandem master cylinder having two fluid chambers disposed along the length of the cylinder, the total length of the reservoir is longer than that of a single chamber type reservoir and thus there is a larger amount of longitudinal expansion of the reservoir.