Charlie writes: I was asked to provide for a local museum an Erector exhibit that demonstrated simple machines such as levers, pulleys and gears. A truck with a crane on it would provide a wide variety of simple machines, so I built this 1928 White Truck chassis of conventional design and mounted a simple crane on the back. The chassis itself is the 1928 version and is of conventional construction except for the use of the later and stronger versions of the DP angle girder. The rubber tires are original.
The side plates of the crane are two Q base plates mounted on a bull ring plate. The crane can be swiveled by means of a crank handle on the back of the truck under the body. That crank handle has a worm gear which drives a large spur gear on a rod which passes vertically through the bull ring plate. I used a Meccano worm gear and a Meccano 95 tooth gear (which would have been available from the A. C. Gilbert Co. during the 1928-1932 period).
The two crank handles on the crane itself control hoisting and luffing. Each one has a CJ gear with an O pawl acting as a ratchet; AE springs (not clearly visible) keep the pawls engaged unless manually lifted. The two BT pierced disks on each crank axle define the ends of the winding drums. This photo should show most of the details. The crane can lift the front of another truck.