Abstract: Presented is a chain tensioner device for chain drives which, because of the environment in which the chain drives are used, must have considerable slack, while operating at high speeds, and yet remain properly engaged to the sprockets on which the chain rotates.

Abstract: Presented is a hydraulic jack structure having a pump assembly in connection with which is rotatably mounted a pump handle assembly which may be rotated in a horizontal plane through about 320.degree. to permit selective positioning of the handle during a pumping operation.

Abstract: Presented is a hydraulic jack structure incorporating an actuating assembly which mutiplies the mechanical advantage between the handle and the pump of the hydraulic jack. A power train is provided interposed between the handle assembly and the pump assembly, increasing the mechanical advantage between the handle and the pump assembly in the order of about 10-to-1. For greater flexibility and convenience during use, the handle assembly, including the power train disposed between the pump assembly and the handle, are mounted so as to be positionally adjusted in relation to the base of the hydraulic jack.