Load crack testing device

Claim 1

A sustained constant load cantilever loading type specimen testing system; which comprises a support means on said support for anchoring one end of a test specimen in place, a cantilever means for securing one end of said cantilever and the unanchored end of said test specimen rigidly together in linear alignment, a hydraulic pressure cylinder containing a piston therein, means for connecting said piston with the free end of said cantilever, a hydraulic fluid reservoir a hydraulic pump means connected to receive fluid from said reservoir, a motor for driving said hydraulic pump to supply hydraulic fluid under pressure to said cylinder, a subplate with interconnected stacked valves connected therewith said valves including in succession a relief valve, a flow control valve and a directional fluid flow valve, said subplate and said stacked valves including sufficient interconnecting fluid pressure lines therethrough to control fluid flow under pressure from said hydraulic pump through said relief valve, said flow control valve and said directional fluid flow valve to said cylinder and sufficient interconnecting return lines to return fluid from said pressure relief valve and said directional flow valve to said reservoir, and a load indicating means for determining stress or strain on said test specimen.