Bruce Hansen writes: This model is a type III Cement Mixer truck model built from a 1963 No. 10129 Master Power set.

The 1963 Master Power was the only set to include a number of parts. This particular model used a couple of them, the #903 Programmer and the #931 Programmer reversing switch.

The #69 Powermatic motor sat between the #903 Programmer and the #95 2-drum hoist and powered both. The hoist shift lever was connected to the programmer with a link bar. In operation, the programmer cycled the hoist between its two drums. When the programmer reached the end of a cycle, a cam tripped the #931 reversing switch which reversed the motor and repeated the cycle.

In operation, the cement truck drove forward while the mixer bucket turned. After a 5-second “drive”, it paused and the dump chute in back lowered. The reverse switch was tripped at this point so the cycle was reversed, the dump chute raised, then the cement truck drove in reverse for 5 seconds.

A couple of trivia comments about this model: The Master Power set had 5 illustrated models, three of them used the #903 programmer. The cement truck model was the only one that used the #931 reversing switch. This model was also the last truck model that had steering. It had a working steering wheel and steering knuckles.