Patent GB-1094074-A (GB)
Abstract: 1,094,074. Wheel balancers; spirit levels. FMC CORPORATION. March 15, 1965 [March 17, 1964], No. 10809 / 65. Headings G1F and G1X. A combined static and dynamic wheel balancer comprises pedestal means 12, wheel mounting means 20 surrounding said pedestal means, a universal bearing 30 for supporting said wheel mounting means on said pedestal means for static balancing, a self-aligning rotary bearing 26 for supporting said wheel mounting means on said pedestal means independently of said universal bearing for dynamic balancing, a handle 36 for selectively supporting said wheel mounting means on either bearing, and weight mean W 4  having a low polar moment of inertia mounted on said wheel mounting means a substantial distance from said self-aligning bearing said distance being sufficient to cause the diametral moment of inertia of the assembly of said weight, balancer and wheelmounting means, to approach the value of the polar moment of inertia of the assembly to an extent adequate to provide a substantial wobble of the wheel caused by a relatively small dynamic unbalance. The tubular pedestal 12 is supported by legs 14 and the wheel mounting means comprises a tube 20 carrying a mounting flange 22. A circular spirit level is mounted in the upper end of the tube 20. The upper end of the pedestal 12 is formed into a damping and seal cup 42 which has an annular internal projection 80 and the lower end of the wheel-mounting tube 20 is formed into a ring paddle 82. During static balancing the paddle 82 is immersed in the liquid 84 and the rod 40 is supported on a pin 52 fixed to the pedestal. The balancer operates on the two plane balancing principle. The wheel is initially balanced dynamically by a weight on the upper wheel rim and then balanced statically by a weight on the lower wheel rim. To prevent excessive tilting while the wheel is spinning up to a dynamic balance velocity the wheel is placed in the spin position Fig. 4 (not shown) by the handle 34 at which time the paddle 82 on the tube 20 closely fits within the annular internal projection 80. After the wheel has been given the desired annular velocity the handle 36 is moved to the dynamic position Fig. 1 and Fig. 5 (not shown). In this position the paddle 82 clears the projection 80 and is largely out of the damping liquid 84. The bubble of the spirit level assumes a position over the vertical axis y-y Fig. 5 (not shown), the colour seen through the bubble indicating the position of the unbalance, and the indicium seen the amount thereof, corresponding weights can then be added. To balance the system statically the handle 36 is operated to bring the universal bearing into contact with the anvil 62 and due to the damping liquid 84 settles quickly into balance, the position being indicated as before on the spirit level. The spirit level L used in the apparatus comprises a circular sectioned glass chamber 90 Fig. 10 (not shown) mounted over an indicia 94 in a tube 88, the upper wall 91 of the chamber being curved over a very large radius. The spacing of the walls 91, 91a is such that the bubble 100 is axially flattened and so provides a clear window large enough to view the indicia. The indicia card is printed in six sectors of different colours and in circumferential rows as shown in Fig.9 (not shown). The liquid is grey tinted so that the only indicia which can be seen is through the bubble.