T-20 & T-21 Hand-Operated Switch Machines

T-20 & T-21


T-20 & T-21 Hand-Operated Switch Machines

The T-20 and T-21 Switch Machines are typically used where facing lock protection is required to help safeguard the movement of high speed mainline traffic over a switch. These machines use a rack and escapement type mechanism and each comes with a circuit controller.

The complete T-20/T-21 operating mechanism is enclosed in a rugged cast iron case with a lockable cover. “T-20” is the basic hand operated switch machine, while “T-21” is a T-20 equipped with a target staff. These switch machines contain a lock bar which, with the switch in the normal position, enters a notch in the lock rod. This arrangement locks the switch points in their normal position to provide facing point lock protection. In addition, the escapement crank mechanism is configured so that the driving system itself locks the switch in either extreme position. Three basic types of circuit controllers are available with the T-20 or T-21 Switch Machines, including standard, standard with reverse point detection, and heavy duty. These contain up to four normally open or closed contacts which are operated jointly by the lock rod and the point detector bar. The contacts indicate whether the switch is in the proper position for facing point moves. In the standard controller equipped for reverse point detection, the reverse detector device contains four additional pairs of contacts that indicate switch points in the reverse direction. The T-20 and T-21 Switch Machines may be used in right or left-hand layouts. Although the machines are externally configured for left or right layouts, all parts are interchangeable to allow conversion to the opposite layout.