Abstract: Disclosed herein are a refractory material of high-purity electrofused magnesia clinker having good resistance to corrosion by slag, especially the slag with a high iron content, at high temperatures under an oxidative environment, and a burned or unburned refractory brick made of such refractory material of high corrosion resistance, which is superior in corrosion resistance as well as spalling resistance.The refractory material comprises more than 10 wt. % of electrofused magnesia clinker containing 98.0 to 99.8 wt. % of MgO, less than 0.05 wt. % of SiO.sub.2, and 0.1 to 2.0 wt. % of CaO. It may be in the form of burned or unburned or prepared unshaped refractories.

Abstract: A brake booster includes a housing in which a constant-pressure chamber and a variable-pressure chamber are defined by a power piston. An input rod is operatively connected to one end of the power piston and receives an input force. A valve is provided in the power piston and operatively connected to the input piston so as to open upon receipt of the input force in such a manner that the differential pressure between the chambers moves the power piston. An output rod is operatively connected to the other end of the power piston. A wall member is provided across which a first auxiliary chamber at a side of the variable-pressure chamber and a second auxiliary chamber formed at a slide of the constant pressure are formed. An orifice passage connects the variable pressure chamber and the first auxiliary chamber.

Abstract: A piston defines in a cylinder housing a pressure chamber connected to a brake pipe and a fluid supply chamber connected to an oil reservoir. The piston has a recess facing the pressure chamber at one end thereof. A valve member is provided in the recess for making or breaking fluid communication between the pressure chamber and the oil reservoir through the supply chamber. A compression spring is disposed in the recess for urging the valve member into its closed position. A spring retainer is fitted about the end of the piston for holding the spring in the recess. A supporting member is provided in the housing on the opposite side of the pressure chamber from the piston. The valve member is supported by a connecting rod extending axially movably through the spring retainer and the supporting member. A compression spring is connected between the spring retainer and the supporting member for urging the connecting rod in the direction which causes the valve member to open.

Abstract: A brake booster for an automobile which includes a reaction disc plate disposed within a central bore of a power piston, one surface of the reaction disc plate contacting the cylindrical member and an opposite side surface contacting force transmitting means wherein one side surface of the reaction disc plate includes a rounded surface complementary to a rounded surface provided on the cylindrical member. A combined cylindrical member and reaction disc plate are utilized such that no space or gap is formed between the cylindrical member and reaction plate so as to shorten the length of the cylindrical member and decrease the time necessary for initiation of brake operation of the brake booster.

Abstract: A tandem diaphragm brake booster includes first and second diaphragms disposed in a housing and a pair of diaphragm pistons which are axially movable for assisting braking efforts through manual operation. The two diaphragm pistons are connected to each other by a key member which also serves to prevent an air valve from accidentally returning.