The MacBone Series MH16, 16,000 BTU/hr., air conditioning unit, is an overhead mounted, unitary, or self-contained unit, with a closed, precharged refrigeration circuit, driven by two, integral, hydraulic motors. Heating is derived from the circulation of hot engine coolant, engine oil or hydraulic oil through the unit. Heating capacity is 18,000 BTU/Hr. at a fluid flow rate of 1.0 GPM at 140° F. The design concept is derived from the need for an operator’s cab air conditioning unit for industrial machines and vehicles where the unit can be quickly removed for service without involving the sealed refrigeration circuit. Cooling is provided by a thermostatically controlled refrigeration system, using refrigerant 134A. The condenser and evaporator blowers share a common shaft, driven by a 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. An auxiliary outside air filter and cab pressurizer is available.
Hydraulic drive input is from a dedicated pump driven by the vehicle's engine or from a compensated pressure source ranging from 2700 PSI to 4000 PSI, capable of a sustained flow rate of 3.25 GPM. Electrical input of 0.8 amps, at 12 or 24 VDC, is used to activate the compressor bypass valve, which allows for the compressor to be cycled by the thermostat. If the MacBone outside air filter / cab pressurizer is used, it will operate at an additional 4.0 amps at 12 or 24 VDC.
All units utilize non-CFC, R-134A refrigerant, measure 26 ¼ x 16 ¼ x 9 1/4 inches high and weigh 85 pounds. Hydraulic lines are #6, supply and return. The motors have external case drains to protect the shaft seals. These are teed together inside the unit and require a #4 drain line back to tank up to 20 ft. Over ft., use #6 drain lines. Four mounting studs provide for quick removal for service or replacement. Recommended operating time before overhaul is 6,000 hours. Recommended unit life is four overhaul cycles.
The MH16 series MacBone units are recommended for operator’s cabs in the 3’ wide x 5’ long range, even if nearly all windows have marginal insulation. With fewer windows and / or significant insulation, the MH16 has proven to be satisfactory on cabs in the 4’ x 6’ range but, to date, we have none on larger cabs.
