[661]. Piston rod fastening.
[662]. Locking feather and wedge fastening, for rollers, &c., prevents end motion.
[663]. Railway chair key.
Section 38.—FRICTION GEAR.
Various forms of friction gearing are much used, the chief objection to this kind of gear being the excess of pressure on the bearings required to give sufficient grip to drive the gear.
[664]. The common form of flat-faced friction gear for hoisting purposes, &c. See [No. 1211]. The required pressure is given by a weighted lever.
[665]. Friction bevils, plain faces, for governor driving, &c.
[666]. Friction bevils, the pinion being usually of hard leather; the pressure may be applied in the direction of either of the arrows.
[667]. Multiple V gear. A common mistake is to run these too deep in gear; the narrower the surfaces in contact, short of the seizing or crushing point, the less the power wasted in friction.