Mike;
The switch on far left is (C11) R.H. drive motor reverse, the next one to the right is R.H. drive motor forward, the third switch (RELAY) would be Hi speed R.H. drive motor forward, the forth Relay would be Hi speed R.H. drive motor reverse, and the following one would be the Line Contactor Relay. L.H. drive motor's direction control relays are to the right of the line contactor. The 19 inch box in the upper left houses the thyristors(SCRs) the main print board and other components of the traction drive's speed controller. After looking through my library the closet material I have to you truck is the E20 323.
A description of the truck's operation is as follows. This series of trucks were equipped with a safety brake switch so that when the parking or foot brake were applied all power was turned off making the truck inoperative.
Power is supplied by a 24 volt battery for all functions. When the battery was plugged in, the ignition switch turned on, and the parking brake turned off, voltage was applied to a zener diode and resistor which applied 8 volts to the card section. Upon depressing the drive pedal the directional switch would actuate and tell the truck which direction to travel. The 10 degree switch turned on the SCR to produce power in the SCR range. The 90 degree switch sent the truck into Hi speed dropping out the SCR speed range. If the motor reach 90% of its speed the Hi speed contactors or bridge contactors would close. When the truck was under a load and the drive pedal depressed were the 90 degree switch was actuated the bridge contactors would close.