An Automatic Sprag Scotch.
Page 21
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E ARE now able to give further details of the interesting spragging device of F. J. Lawrence (specification No. 196,796) which was mentioned amongst the recently published patenti in The Commercial Motor on June 19th. This consists of a combined sprag and scotch of neat and original design. As . shown in the diagrammatic illustration, a shaft is carried on brackets above and
behind the axle. On this shaft are mounted a cast-iron bottle loaded with mercury, the sprag, and a bell-crank lever.
When the vehicle is on level ground the balance of the bottle is such that the sprag is lifted and the bell-crank rests on a buffer fixed to the axle. When a rise is encountered the mercury runs backward in the bottle and causes the sprag to trail.
The novelty consists in the means adopted for placing a scotch under the wheel. If the vehicle commences to run back the sprag digs into the road. This operates a spring-loaded quick-thread screw, and so causes .the scotch to; revalve and come into position under aml
behind the wheel. .
In. order to Make it passible to run the vehicle backwards downhill . when de
sired, a cable connection is taken to the reverse gear in such a way that, when the reverse is operated the cable is pulled. This has the effect of tightening the slack chain shown, and so raises the sprag