Hydraulic torque wrench

A hydraulic torque wrench, comprising:

• a head having an input for pressurised hydraulic fluid, a rotatable connector for connecting to an item to be rotated by the hydraulic torque wrench, and a drive mechanism driven by hydraulic fluid introduced at the input and tending to rotate the rotatable connection;
• and
• a reaction arm mounted on the head through a mounting which selectively allows rotational motion of the reaction arm relative to the head about an axis, the reaction arm arranged to react against a surface when the drive mechanism rotates the rotatable connection;
• in which the mounting comprises:
• a splined connection, comprising complementary splines on the head and the reaction arm, which permits linear motion of the reaction arm relative to the head along the axis from a first position where the splines of the splined connection interengage so as to prevent relative rotation of the reaction arm and the head, and a second position where the splines of the splined connection do not interengage and allow relative rotation of the head and the reaction arm;
• and
• a linear travel limiter which prevents linear motion of the reaction arm relative to the head past the second position, comprising a rigid elongate member attached to the head, with a step on the reaction arm engaging a stop on the rigid elongate member to stop the linear motion past the second position.

A hydraulic torque wrench, comprising:

• a head having an input for pressurised hydraulic fluid, a rotatable connector for connecting to an item to be rotated by the hydraulic torque wrench, and a drive mechanism driven by hydraulic fluid introduced at the input and tending to rotate the rotatable connection;
• and
• a reaction arm mounted on the head through a mounting which selectively allows rotational motion of the reaction arm relative to the head about an axis, the reaction arm arranged to react against a surface when the drive mechanism rotates the rotatable connection;
• in which the mounting comprises:
• a splined connection, comprising complementary splines on the head and the reaction arm, which permits linear motion of the reaction arm relative to the head along the axis from a first position where the splines of the splined connection interengage so as to prevent relative rotation of the reaction arm and the head, and a second position where the splines of the splined connection do not interengage and allow relative rotation of the head and the reaction arm;
• and
• a linear travel limiter which prevents linear motion of the reaction arm relative to the head past the second position and at least one biassing member which acts to bias the reaction arm into the first position.