Patent GB-934552-A (GB)
Title: Improvements in control mechanism for conveyor track switches
IPC: E01B25/26
Filed: 1962-02-21
Abstract: 934,552. Conveyer truck switches. JERVIS B. WEBB CO. Feb. 21, 1962 [Feb. 24, 1961], No. 6732/62. Class 104 (2). A switch tongue position control mechanism for a conveyer carrier track system having a switch tongue 12 pivoted at an intersection of the main and branch lines 10, 14 and held by a latch device in the main line 10 position against the force of a shifter spring 38 which acts to move the tongue 12 to the branch line 14 position when the latch is released, operates as follows. Assuming a carrier has been diverted to the branch line 14 and the switch tongue 12 has been reset to the main line position shown in Fig. 1 and in full lines in Fig. 2, the tongue 12 will be held in this position by rollers 36 engaging a shoulder 48, Fig. 5 (not shown), of a latch member A pivotally mounted on a spindle 42 and held in this position by a spring 50. The diverted carrier on reaching a sensing unit 16 contacts, by means of a carrier drive pin, an arm 56 which is pivoted clockwise to move a control cable 21 which, in turn, partially rotates a latch member B about the spindle 42. During the rotational movement the latch member B engages a depending lug 62 on the latch member A and moves the latch member A from a latch retaining to a non-retaining position and the latch B to a retaining position. As the latch A reaches the non-retaining position a resetting member 30 is moved about a pivot 31, by means of which the member 30 is secured by an arm 28 to the tongue 12, by the spring 38 thus placing the rollers 36 in engagement with the surface 52 of the latch member B and in blocking engagement with a side portion 59 of the latch member A. When the carrier passes the sensing unit 16 a spring 54 returns the arm 56 to its normal position and in so doing returns the latch member B to a non-retaining position, Fig. 8 (not shown), permitting the member 30 and hence rollers 36 to move into engagement with a shoulder 49 on a latch member C. When a carrier on the main line 10, destined for the branch line 14, approaches a sensing unit 20 a detecting unit 18 operates to effect the projection of a plunger 66 into the carrier path which plunger 66 is engaged by the carrier drive pin to  rotate the sensing unit 20 about a pivot 64 to operate control cable 22 connected to the latch members C. The latch member C is rotated counterclockwise about the spindle 42 releasing the rollers 36 from the shoulder 49 of the latch member C thus permitting the resetting member 30 to be moved about the pivot 31 by the spring 38 into engagement with the stop 40 carried by  arm 28 and to swing the tongue 12 to the branch line position shown dotted in Fig. 2. In the branch line position a cam 32 of the resetting member 30 extends across the slot 14a of the branch line 14 in a position for  engagement by the drive pin 68 of a diverted carrier. The drive pin 68 firstly engages a cam portion 69 of the cam 32 to move the resetting member counterclockwise about pivot 31 into engagement with the stop 40 to effect clockwise movement of the tongue 12 to the main line  position and, secondly, the pin 68 engages a cam portion 70 of the cam 32 to rotate the resetting member 30 clockwise to move the rollers 36 into a position in which the rollers 36 are engaged by the latch member A which is moved to the locking position by the spring 50.