AC powered dock leveler controls two single acting dock cylinders. Valving: integrated sequence, shuttle, logic, and throttle valves (see drawing). On/Off only, no remote needed. Customer will be required to wire unit. Dock levelers of this type utilize two single acting cylinders; one to raise the entire dock plate and the other to extend the lip that bridges the gap between the dock plate and the trailer. The operation is the same in both units, to place the dock in the loading position the unit’s AC motor is energized. Oil is sent to cylinder #1 which raises both the dock plate and the lip to an approximate 45o angle. When cylinder #1 is fully extended, a sequence valve sends oil to cylinder #2 to extend it. When cylinder #2 is fully extended, the motor is de-energized, allowing cylinder #1 to retract and briefly holding cylinder 2 extended. To release the trailer, the motor is energized extending cylinder #1, as the plate raises cylinder #2 is allowed to retract letting the lip fall back to a vertical position. When cylinder #2 is fully retracted, the motor is de-energized allowing cylinder #1 to retract and the dock to rest as pictured This unit is similar to the Maxim #253131 in fit, form, and function with these differences: The Chief unit is 1” shorter in length overall. This is due to the length of the AC motor. The Chief unit is 0.3” taller on the tank end and 2.5” shorter on the motor end. This is due to the motor’s capacitor box is mounted on the side instead of the top. Both units are identical in width. The Chief unit motor foot mount is 0.2” shorter. Functionally they are very similar, the main difference is the Chief unit offers a throttle valve with a knurled knob allowing the retract speed of cylinder #1 to be adjustable in the field. While the Maxim unit offers this as well, it is adjusted by loosening the nut around the adjustment screw and using an Allen-wrench.