Cars that are to be classified are pulled west out of the receiving yard and then shoved back to the hump, which at West Colton is on a descending grade. This is the reason the retired Train Masters were tried out as braking sleds. In a normal humping operation tractive effort is used to push cars up to the crest where they are cut off and roll down into the classification yard. At WC the locomotives control the speed of the hump cut with braking power.

But lets get back to a discussion of motive power. After the Alcos were sidelined West Colton used an assortment of power including SD35's as well as the SD39's in tandem with 6-axle slugs manufactured from some of the Alcos.