Abstract: A servo amplification system is created particularly for heavy construction equipment, but has a general utility that is much broader. The system utilizes a hydraulic analog system with a separate subsystem for each dimension of motion. The operator moves the operative element, such as the backhoe bucket, of the analog replica which ordinarily would be situated in the cab of the backhoe or other piece of equipment. A small hydraulic cylinder operative in response to movement at each articulated connection of the backhoe operates a pilot valve which controls a pilot piston mechanically linked to the drive valve of the drive cylinder of the corresponding articulation in the actual backhoe. A feedback system comprising a mechanical link from the actual drive piston to a feedback cylinder and piston delivers hydraulic fluid back to the inlets of the pilot valve in such a way as to cancel the pilot orders from the initial control cylinder.

Abstract: A servo amplification system is created particularly for heavy construction equipment, but has a general utility that is much broader. The system utilizes a hydraulic analog system with a separate subsystem for each dimension of motion. The operator moves the operative element, such as the backhoe bucket, of the analog replica which ordinarily would be situated in the cab of the backhoe or other piece of equipment. A small hydraulic cylinder operative in response to movement at each articulated connection of the backhoe operates a pilot valve which controls a pilot piston mechanically linked to the drive valve of the drive cylinder of the corresponding articulation in the actual backhoe. A feedback system comprising a mechanical link from the actual drive piston to a feedback cylinder and piston delivers hydraulic fluid back to the inlets of the pilot valve in such a way as to cancel the pilot orders from the initial control cylinder.

Abstract: A torque multiplier assembly that is portable, compact, and may be easily and conveniently disposed adjacent a nut, bolt or similar threaded elements to removably engage the same. The torque multiplier assembly when so engaged is adapted to exert a first relatively high maximum torque of predetermined value on the nut, bolts or similar elements to initially rotate the same from binding threaded engagement or perform the final tightening of the nut bolt or rotatable element. The torque multiplier assembly is manually actuated by the use of an elongate torque wrench of a type that is commercially available and may be adjusted to supply any one of a number of maximum torque. The desired maximum torque supplied by the elongate torque wrench is relatively low, normally not over fifty foot pounds, and is visually indicated on a calibrated scale that forms a part of the torque wrench.