Abstract: A transport refrigeration unit for mounting on the front face of a trailer 1 or the like is provided with an exterior section 2 construction and arrangement in which a relatively low center of gravity is obtained by providing a frame means 25 in the lower portion of the exterior section mounting an internal combustion engine 26 at a relatively low level with a refrigerant compressor 27 at a somewhat higher level, and an electric motor 28 below the compressor when such a motor constitutes a part of the power pack, these elements being arranged so that the driving belts and pulleys in the lower part of the section are in the center portion of the section to promote their accessibility, and a significant open area is provided above the power pack to promote access to those parts in the upper portion of the exterior section behind the condenser 9.

Abstract: A hot gas pressure switch 29 is provided to be responsive to pressure in a hot gas line 22 which will have a significant pressure value only during a heat or defrost mode, to unload cylinders of a transport refrigeration compressor to avoid overload, so that the compressor can operate with a substantially greater discharge pressure in a cooling mode without penalty.

Abstract: A transport refrigeration system having the capability of either heating or cooling at high or low speed and with the compressor loaded or unloaded is controlled by a temperature control system including a heat relay 1K and a speed relay 2K, and has an auxiliary control relay CR which is operative to maintain the compressor speed at a low speed in the temperature band 48 closely above and below the setpoint temperature, and will further maintain the low speed of the compressor for a predetermined time as the temperature rises above or below the narrow temperature band through time delay means 46 which, if uninterrupted in operation for the predetermined time period will drop out the control relay so the system can resume higher speed operation.

Abstract: An internal combustion engine starting circuit for a system including a combination direct current motor generator unit having an armature coil and field coil in series therewith to be connected to a source of direct current to function as a starter motor when the ignition switch is first closed and to function as a generator when the internal combustion engine starts to bring the motor generator unit to generating speed is provided with a starting solenoid to be energized to close a contact for connecting the motor generator unit to the source when energized. An ignition switch is adapted to be closed to complete a circuit through one coil of a double coil starting relay having a normally open contact to be closed to energize the starter solenoid in series with the ignition switch and the source.

Abstract: A multi-position throttle mechanism is comprised of a link body having first and second servo devices secured thereto with the free end of the servo arm of one servo device connected to the engine frame and the free end of the arm of the other servo device connected to the throttle lever pivotally mounted on the engine whereby selective actuation of one or the other or both or neither of said servo devices results in at least three selectively different pre-set throttle positions.