GB298662A - Improvements relating to penetrometers - Google Patents

Abstract

298,662. Griffiths, E., and Griffiths, E. A. July 12, 1927. Testing hardness of materials. - A penetrometer more especially for testing the hardness of fruit and substances of similar consistency comprises a bluntnosed plunger and encircling guard ring which bears upon the surface to be tested, and means for measuring the resistance offered to causing a predetermined penetration of the plunger relatively to the guard ring. A bluntnosed plunger a attached to a rod e secured to a block g and tube h by a bolt f is mounted centrally in a guard ring b secured to a tube d which is adapted to slide within the tube h but is prevented from relative rotation thereto by a screw l engaging a slot m in the tube d. The tube h is adapted to slide in a tube i to which is secured a knob j, a screw w engaging a slot in the tube h to prevent relative rotation. Located between the block g and the knob is a spring k. An adjustable screw abutment r on the tube i is adapted to engage the plunger of a dial gauge o carried by the tube h. A light spring c serves to keep the plunger extended. In use, the guard ring is applied to the surface of the fruit to be tested and pressure exerted on the knob. When the surface is penetrated to sufficient extent, the tail u of a trigger t engages the hole r and the end q<1> of the plunger is gripped by the trigger mechanism to cause the gauge to retain the reading on removable of the device. Upon release of the trigger mechanism the reading of the gauge is restored to zero by a spring.