Section 20.—COMPENSATING AND BALANCE WEIGHTS.
It is of the utmost importance that every revolving or reciprocating part of any machine should be as nearly as possible balanced, to obtain smooth running with the least amount of wear.
The following are types of the most important devices and their applications:—
[369]. Balanced lever, having a sliding cheese or ball weight fixed with a set screw.
[370]. Balanced cage of hoist. It is usual to over-balance the cage to divide the work between the up and down journeys in hand-power lifts to assist the load; but in power and hydraulic lifts the cage is under-balanced so as to descend when empty.
[371]. Hydraulic balance lift, in which the dead or constant load of cage and ram are nearly balanced by a loaded piston in a supplementary cylinder; to raise the loaded cage the pressure water is admitted to the upper side of this piston. Many varieties of this type are in use; see Ellington’s, Johnson’s, Stevens and Major’s, Waygood’s, and other patent lifts.
[372]. Variable volute compensating balance for revolving shutters, blinds, curtains, &c., to maintain an even balance in all positions, The weight chain is as thick as the coiling shutter on blind, so that the acting radii of the shutter and weight are always proportional.
[373]. Variable compensating balance for hydraulic lift rams, to compensate for loss of immersion of the ram as it ascends (Berly’s patent). See also Stevens & Major’s patent, where bell-crank levers and weights are employed instead of loaded chains. See [No. 383].
[374]. Balanced fly-wheel. For balanced cranks, see [Nos. 172] & [173].
[375]. Increasing balance by sections, lifted at intervals as the chain rises.