Patent ID: 7690864
Filing Date: 2010-04-06
Classification: E04F

Abstract:
1. A motorized, hydraulic riding trowel for finishing concrete, said riding trowel comprising: rotor means pivotally suspended from said riding trowel, said rotor means comprising a plurality of radially spaced apart blades for frictionally contacting the concrete; steering means for tilting the rotor means to effectuate trowel steering, maneuvering, and propelling; joystick means accessible to a trowel operator for selectively activating said steering means, whereby the operator of the trowel can steer and control the riding trowel hydraulically; one or more hydraulic drive motors for rotating said rotors; primary hydraulic pump means for supplying hydraulic flow under pressure to said drive motors; pump control head means for controlling said hydraulic pump means for supplying flow and pressure to said drive motors; a control head (PCH) control line for controlling said pump control head means; user operated foot-pedal valve means for controlling said primary hydraulic pump means by pressuring said PCH line; and, unloader valve means for dynamically responding to varying friction and load fluctuations encountered in trowel use and generating an unloader pressure signal (UPS), the unloader valve means comprising: