Cap positioning mechanism

A roof cap for a mine roof unit, the roof cap comprising a main cap, an auxiliary cap connected to the main cap by a first pivot joint, and a cap-positioning mechanism for adjusting the angular position of the auxiliary cap relative to the main cap, the mechanism comprising a hydraulic ram and a lever acting between the main cap and the auxiliary cap, wherein the auxiliary cap is provided with an extension arm projecting from the first pivot joint towards the main cap, one end portion of the lever being connected to the arm by a second pivot joint, and the other end of the lever being connected to a first part of the ram by a third pivot joint, the lever having a length which is less than the distance between the first pivot joint and the third pivot joint, a second part of the ram being attached to the main cap, the first and second parts of the ram being relatively movable.

A roof cap for a mine roof support unit, the roof cap comprising a main cap, an auxiliary cap connected to the main cap by a first pivot joint, and a cap-positioning mechanism for adjusting the angular position of the auxiliary cap relative to the main cap, the mechanism comprising a hydraulic ram and a lever acting between the main cap and the auxiliary cap, wherein the auxiliary cap is provided with an extension arm projecting from the first pivot joint towards the main cap, one end portion of the lever being connected to the arm by a second pivot joint, and the other end of the lever being connected to a first part of the ram by a third pivot joint, a second part of the ram being attached to the main cap, the first and second parts of the ram being relatively movable;

• and said roof cap further comprising a second lever one end of which is connected to the first part of the ram by the third pivot joint, the other end of the second lever being connected to the main cap by a fourth pivot joint.