Abstract: A carriage lock selectively enables and prevents a mobile carriage from moving along rails embedded in a building floor. The mobile carriage includes a shaft on which are rotatably mounted a driver sprocket, a hub, and a handwheel. The hub mates with the driver sprocket. A chain and sprocket mechanism connects the driver sprocket with the carriage wheels such that rotation of the handwheel and hub causes the carriage to move along the rails. A locking knob is loosely captured between the hub and handwheel for being manually rotated through a predetermined angle relative to the hub and handwheel. A pin is translatable within the hub parallel to the shaft longitudinal axis. The pin has a head that is received within a selected one of two angularly spaced depressions in a cam formed on the locking knob. The depressions are also spaced apart in the direction of the shaft longitudinal axis.

Abstract: A mobile carriage is movable along rails by manual rotation of a handwheel. The mobile carriage comprises a visual indicator that instantly informs a person of the locked or unlocked status of the mobile carriage. The visual indicator comprises at least one ridge on the handwheel and another ridge on a locking knob. The locking knob is loosely captured between the handwheel and a hub for selective rotation relative thereto between first and second end positions. The locking knob has a cam that slides a pin within the hub between first and second positions whereat the pin disengages and engages a stationary lock plate. When the locking knob is manually rotated to the first end position thereof, the pin disengages from the lock plate to enable handwheel rotation and carriage movement. Manually rotating the locking knob to the second end position thereof causes the pin to engage the lock plate and prevent handwheel rotation and carriage movement.