The purpose of this work is in line with the general research program for the crushing plant, that is, to obtain as much technical information regarding all phases of oil shale crushing as possible. The aim is toward information that can be used for the design and layout of commercial size units. In this case, the 42" Allis-Chalmers gyratory is being investigated as a possible primary breaker. The use of this crusher affords an opportunity for collecting data not ordinarily afforded, as the size and cost of this crusher would definitely prohibit its installation and use at this station. It should be pointed out that obviously no crusher throughput capacity tests could be made at this time because of the relatively short time the crusher could be used.