Abstract: A multifunction relief valve includes a relief chamber having an introduction port and a relief port for introducing and relieving pressure fluid; a back pressure chamber formed on one end side of the relief chamber; a piston which is movably provided in the back pressure chamber and divides the back pressure chamber into a first back pressure chamber and a second back pressure chamber; a first spring which is provided in the first back pressure chamber and exerts a biasing force in a direction in which the relief port is closed; a second spring which is provided in the second back pressure chamber and biases the piston in the direction in which the relief port is closed; and a pilot pressure supply port formed in the first back pressure chamber. The pressure fluid introduced into the first back pressure chamber via the pilot pressure supply port changes the relief pressure.

Abstract: The present invention provides a technology for downsizing fluid pressure equipment including a fluid pressure pump and a radiator. The hydraulic pump unit 3 includes: a hydraulic pump 4; a motor 5 which drives the hydraulic pump 4; a cooling fan 7 which is connected to an output shaft 5a of the motor 5 and generates a flow of cooling air 6 to cool the motor 5; and a radiator 8 which receives heat from the hydraulic oil. The motor 5 and the radiator 8 are overlapped with the cooling fan 7, when viewed from the axial direction of the output shaft 5a of the motor 5.

Abstract: A multifunction relief valve 1 includes: a relief chamber 2 having an introduction port 7 and a relief port 8 for introducing and relieving pressure fluid; a back pressure chamber 3 formed on one end side of the relief chamber 2; a piston 4 which is movably provided in the back pressure chamber 3 and divides the back pressure chamber 3 into a first back pressure chamber 3a and a second back pressure chamber 3b; a first spring 5 which is provided in the first back pressure chamber 3a and exerts a biasing force in a direction in which the relief port 8 is closed; a second spring 6 which is provided in the second back pressure chamber 3b and biases the piston 4 in the direction in which the relief port 8 is closed; and a pilot pressure supply port 9 formed in the first back pressure chamber 3a. The pressure fluid introduced into the first back pressure chamber 3a via the pilot pressure supply port 9 changes the relief pressure.

Abstract: The present invention provides a technology for downsizing fluid pressure equipment including a fluid pressure pump and a radiator. The hydraulic pump unit 3 includes: a hydraulic pump 4; a motor 5 which drives the hydraulic pump 4; a cooling fan 7 which is connected to an output shaft 5a of the motor 5 and generates a flow of cooling air 6 to cool the motor 5; and a radiator 8 which receives heat from the hydraulic oil. The motor 5 and the radiator 8 are overlapped with the cooling fan 7, when viewed from the axial direction of the output shaft 5a of the motor 5.

Abstract: A process for purifying methyl methacrylate which comprises treating methyl methacrylate having a purity of 99.5% or more containing a trace of impurities with a sulfonic acid group-containing compounds. According to the present invention, there can be obtained highly purified methyl methacrylate which exhibits an absorbance of 0.02 or less in a range of wavelength of 400-500 nm according to the sulfuric acid color method and is free of even a trace of furan-type compounds.

Abstract: Highly purified isobutylene, up to 99.9% pure, is obtained by treating a reaction mixture such as that recovered from an isobutylene-containing hydrocarbon mixture also containing an aqueous solution of an aliphatic carboxylic acid having 1 to 6 carbon atoms that has been reacted in an acidic ion exchanger and from which the unreacted hydrocarbons have been removed. The operative ingredients of the treated mixture are tertiary butyl alcohol, secondary butyl alcohol and their esters of the carboxylic acid employed. When treated with an acidic ion exchanger the carboxylic acid is first formed which inhibits the secondary butyl alcohol and secondary butyl ester of the acid from decomposing and high purity isobutylene is recovered therefrom by conventional distillation.

Abstract: A method of removing chromium ion from an aqueous solution of an organic acid of an acid concentration of up to 95% which comprises treating the solution with a cation exchange resin at a temperature higher than 55.degree. C.