Heating system for machine operator's cab

Abstract

A machine, such as a self-propelled mobile crane, having an operator's cab and an engine for driving hydraulic pumps to supply fluid to hydraulic motors which drive crane components, is provided with a heating system for the operator's cab. The heating system comprises a heating system hydraulic pump driven by the engine, a fin-and-tube-type heat exchanger located in the cab, a pilot-fluid operated adjustable unloading pressure relief valve connected in circuit between the heating system hydraulic pump and the heat exchanger, and wherein hydraulic energy is converted to thermal energy because of a large pressure drop therein; a solenoid valve for adjusting the pressure relief valve to control the hydraulic fluid pressure drop and, therefore, temperature, and prevent excessive temperature; a first thermostat responsive to the hydraulic fluid temperature for controlling the solenoid valve; a motor-driven adjustable-speed fan in the cab for directing air across the heat exchanger to heat the air in the cab; and a rheostat or multispeed switch to control fan speed and, thus, the rate of heat transfer between the heat exchanger and the cab air and thus, cab air temperature.

Dependencies are inferred from the claim text.