GB686935A - Improvements in or relating to deflation indicator for pneumatic tyres - Google Patents

Abstract

686,935. Pneumatic tyres. WOOLF, H. H. Nov. 20, 1951 [Nov. 21, 1950], No. 28418/50. Class 144 (i). A device for indicating tyre deflation in running comprises a pivoted feeler rotating with the wheel and resiliently constrained to engage the side-wall of the tyre, the displacement of the feeler on fall of pressure in the tyre being utilized to close a circuit including a fixed contact, a second contact rotating with the wheel, and a visible (or audible) signal. The invention is shown applied to twin wheels 10, 11 bolted to the brake-drum 15 which is fitted with a two-part metal ring 17 carrying, on lugs 19, tubular casings 21 of the rotary contact devices 20. A plunger 24 extending through end-plugs 22, 23 of the casing 21 is urged outwardly by a spring 25 to maintain the feelers 36, 38 in contact with the tyres 13, 12 respectively. The inner end of each plunger is fitted with a nut 28 bearing against a disc 27 on the plunger, a light spring 29 being normally compressed between the disc 27 and plug 23. Rounded heads 30 screwed on the discs 27 form the movable contacts which are arranged to co-operate with diametrically-spaced fixed contacts 45 carried by brackets 48 mounted on the axle-casing 14. The feelers 36, 38 are pivoted on brackets 34, 35 carried by the casings 21. The feeler 36 (for the inner wheel) is engaged directly by the projecting end of the corresponding plunger 24, the plunger 24 associated with the feeler 38 (for the outer wheel) being actuated by an intermediate rocking lever 40. As shown in broken lines in Fig. 4, the flattening of the deflated tyre, at the ground-engaging portion, results in the plunger being forced inwardly to move the nut 28 away from the end disc 27 whereupon the spring 29 reacts to move the head 30 to engage the fixed contact 45 and close the signal-circuit.