It must be understood that the pivots or axis, j, j, n, t, hereinafter referred to, on which certain parts are mounted, are supported by and extend between the two parallel rims, radial arms, and bosses of the wheel, b, c, d. e, e are curved arms working on axes or pivots, j, fixed in the rims; each arm carries weights, g, g, held in place by adjusting screws g'. Each arm, e, terminates at its innermost end in a wheel, h, toothed on a portion of its periphery, through which the weight, v, forces the weights, g, outward at the right-hand side of the wheel, causing a preponderance of weight on that side.