Patent ID: 6382059
Filing Date: 2002-05-07
Classification: B25B

Abstract:
An improved system for installing and removing bolts and nuts from flanged joints in both a high torque phase and a low torque phase which comprises:a) a wrench body having first and second end portions with a rotatable drive head on the first end of the body for engaging and rotating the bolt or nut; b) a high-torque motor that includes a hydraulic cylinder attached to the wrench body for receiving fluid under pressure for rotating the drive head during the high-torque phase, the cylinder having an extendable pushrod operatively connected to the drive head enabling said rotation; c) a low-torque motor which is also operatively connected to the drive head and rotates the bolt or the nut during the low-torque phase of removal or installation; d) a source of pressurized hydraulic fluid; e) a plurality of flow lines for transmitting fluid between the fluid source and the high and low-torque motors, including a first pair of flowlines that communicate with the low-torque motor and a second pair of flowlines that communicate with the high-torque motor; f) a valving member that, upon reaching a pre-selected high-torque value, opens responsive to increasing fluid pressure to divert fluid flow to the high-torque motor for driving the high-torque motor during the high-torque phase; g) wherein the valving member senses fluid pressure and diverts flow to thereby define the high-torque and low-torque phases; and h) the valve member automatically opening or closing responsive to a change in fluid pressure to selectively drive the high-torque motor or the low-torque motor depending on the torque value required, wherein the valving member diverts fluid flow without the use of strain gauges, solenoid valves, or electronic pressure switches.