THE MECHANICAL HANDLING OF MATERIALS 291
fully extended. The section of the second length. is made up of two steel channels-connected together by means of steel cover plates. This length has fitted at the back end four rollers running on cast-steel pivots. The rollers are of suitable size for running within the
channels which form the third length. The stroke of the second length. is governed by stops fixed in the front end of the
third length with which the front rollers come in contact, thus ensuring a rigid bearing when fully extended. The t h i r d length. is of similar but larger section to that of the second length. This length is also fitted with four rollers running on cast-steel pivots. These
rollers are of suitable size for running within the fixed channels which form the lower portion of the h angi ri g frame, which is fitted with stops at the front end
Pig. 209.—The Jenkins-De Bbouwbb Dischargina Pusher, showing the Telescopic Ram fully EXTENDED.
so that the third, length also has a rigid bearing when at its extreme outward stroke.
On the underside, at the front end of the hanging frame, there is a steel rack pinion keyed to a shaft on the end of which is fitted a steel spur wheel to gear with