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The MacBone model CH24, 24,000 BTU/hr., cooling and heating unit, is an overhead mounted, unitary, or self-contained unit, with a closed, precharged air conditioning circuit, driven by a single, integral, hydraulic motor. The design concept is derived from the need for a cooling and heating unit for industrial applications where the unit can be quickly removed for service without involving the sealed refrigeration circuit. Cooling is provided by a thermostatically controlled automotive type compressor, using refrigerant 134A, with heating derived from engine hot water or hot oil. The condenser fan and evaporator blower share a common shaft, driven by the hydraulic motor, with sufficient power to produce substantial condenser air flow even with a filter on the outside coil, thus insuring reliable performance even in a heavily dust laden environment. Substantial power delivered to the inside air blower also assures delivery of full system capacity under all conditions. Induction of 10% outside air provides cab pressurization to exclude dust and other contaminants from entering the cab environment.

Hydraulic drive input, from a pump driven by the vehicle's engine and utilizing the vehicle's hydraulic reservoir, is 10 GPM at a maximum pressure of 1300 PSIG. System pressure relief, provided by the installer, should be set at 1650 PSI. Electrical requirement is 3 amps at 12 or 24 volts D.C. Electrical input is used only to activate the compressor clutch and all MacBone units will accept power from 10 to 28 volts D.C.

For the CH24, an optional sub base with shock mounts is available. All units utilize non-CFC, R-134A refrigerant, measure 36.5" x 24.5" x 12.5" inches high and weigh 165 pounds. Hydraulic lines are #8, supply and return, up to 40'. The motor has an external case drain to protect its shaft seal. Four 1/2 inch SAE mounting bolts provide for quick removal for service or replacement. The dual V belt drive system has an automatic tensioner and operates in a closed, ventilated area. Original estimated operating time before overhaul, under severe conditions at full speed and load, was 4000 hours with expected unit life of three overhaul cycles. We note, however, that at the end of the 1999 season, we were servicing units with up to 6000 hours which needed belts only. We also note that three overhaul cycles will not be the limit.