Position sensing device for sensing an upper limit position and a lower limit position of a hoisting line

摘要

A position sensing device for sensing an upper and a lower limit position of a hoisting line 22 for a door leaf 12 of an animal enclosure 100. The device comprising an actuator arm 28 moveable between a first and second position, wherein the actuator arm 28 is biased to the first position, a proximity switch 35 having a first state corresponding to arm 28 being in the first position and a second state corresponding to the actuator arm 28 being in the second position. The actuator arm 28 configured to cooperate with a hoisting line 22 such that when line 22 is in an intermediate position and is under tension, it bears against arm 28 to move the arm 28 to the second position. When a suspended load is relieved from line 22 in its lower position, the actuator arm 28 moves under bias to the first position. The arm 28 engages with a portion 40 on the line 22 as the line 22 rises to move the arm 28 into the first position when the hoisting line is in its upper limit position.