Patent ID: 8360680
Filing Date: 2013-01-29
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; manually operated control levers for tilting the rotor means to effectuate trowel steering, maneuvering, and propulsion; hydraulic drive motor means for rotating said rotor means; primary hydraulic pump means for supplying hydraulic flow pressure; pump control head means for controlling said primary hydraulic pump means for supplying flow and pressure to said hydraulic drive motors; a pump 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 pump control head (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: