Fan drive having pressure control (fluid) of a wet friction fan drive

摘要

A hydraulically controlled fan drive system (12) having a method of engagement includes a housing assembly (20) containing a hydraulic fluid (48) and an engaging circuit (36). The engaging circuit (36) includes a pitot tube (152) coupled within the housing assembly (20) that receives at least a portion of the hydraulic fluid (48). An engaging circuit (36) engages the housing assembly (20) to a fan shaft (44) in response to supply of the hydraulic fluid (48) from the pitot tube (152). An electrical control circuit (40) having a relief valve assembly (225) coupled to a main controller (176) is used to control the fluid pressure within the pitot tube (152) that controls the engagement of the housing assembly (20).