Method and apparatus for certifying the output torque curve of a

Abstract

Disclosed herein is a method and test apparatus for use in determining and certifying hoist compliance with one of several minimum body and payload torque requirement curves, which curves establish torque classifications for hydraulic hoists suitable for use in dump body applications. The apparatus is made up of a base frame which simulates a truck chassis, and an upper frame pivotally connected to the base frame and which simulates the under-structure portion of a dump body. The test hoist is mounted to the base and upper frames so that the hoist can be rendered operative to pivot the upper frame through a predetermined range of dump angles. Longitudinally adjustable tension link or estraining arm assemblies are connected to the base and upper frames and are used for successively restraining the pivotal movement of the upper frame to predetermined incremental dump angles within the predetermined range of dump angles. The link assemblies include tension load cells for providing outputs proportional to the longitudinal forces exerted on the link assemblies. A hydraulic pressure source supplies fluid to the hoist at the hoist manufacturer's maximum rated pressure so that the test hoist is operative to pivot the upper frame. Instrumentation is connected to the outputs of the tension load cells to process the outputs to provide a readout of the longitudinal forces exerted on the tension link assemblies at each incremental dump angle so that the torque exerted by the hoist can be determined.