Drop roller

Ball- and roller-bearing materials ate commonly selected to provide a minimum Rockwell hardness of 58—60 R at load-carrying contacts (37,38). Below this level, fatigue strength drops so rapidly as to seriously impair the utiUty of a material for rolling beatings which involve contact stresses in the 700—2800 MPa... 

Because of the steep pitch required, slides are limited in application. They are most commonly used to bridge the gap between roller-conveyor systems on two floors, because the roller conveyor can take the container off the slide rapidly and ehminate or reduce the chance for collisions. Slides may also be used when containers can be chuted from an upper floor to a manually loaded carrier. The use of several rollers at the feed point is recommended for easy dehveiy to the sloping section. If the drop is short and containers light, a roller cleanout will prevent backup of containers on the slide. The slope of gravity slides is a function of container weight, size, and friction characteristics and should be selected with care to be sure that containers do not move either too swiftly or not at all. Slides usually use flat steel sheet. 

Roller rock bit nozzle sizes are given in Table 4-98. The total pressure drop across a roller rock bit, Pj (psi), is [47]... 

A tricone roller rock bit is furnished with three nozzles with the diameters of 32 od -il in. Calculate the bit pressure drop if the mud weight is 10 Ib/gal and flowrate is 300 gpm. 

The steel roller with the sample powder is placed in the center of the anvil on the drop ball test equipment... 

A steel ball 7mm in diameter 0 (about 1.4g) is dropped onto the upper steel roller to provide a percussive shock to the samples from a height of H = 10cm (log H = 1.0). The samples are graded as "go" or "no go". The samples which explode and emit sound, fire and smoke are judged a "go" (they react). 

The steel roller is quickly placed on the anvil of the drop test equipment. 

The steel ball is dropped on the upper roller by cutting off the magnet switch. 

Fig. 6.1 Drophammer in accordance with the BAM (a) and detailed sketch of the drop-hammer test with the two steel rollers, a hollow steel collar and a centring ring for fixation (b).

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