Patent GB-652866-A (GB)
Title: A device for use when retreading tyres
IPC: B29B17/02
Filed: 1947-03-20
Abstract: 652,866. Repairing tyre covers. AUTO TYRE SERVICES, Ltd., and KENT, J. H. F. March 20, 1947, No. 7742. [Class 144 (i)] [Also in Group VIII] The invention concerns an apparatus for rasping or cutting the tread of a tyre for retreading, wherein the tyre is caused to revolve and pressure is applied to the tyre side walls to produce local flattening of the tread, the cutting operation being controlled by relative displacement of the respective axes of rotation of the tyre and the rasp or cutter towards or away from each other, and the amount of tyre spread. In one form of the invention side wall pressure for flattening the tread is applied at the tyre beads and solely in the vicinity of the rasp or cutter, and in a further form of the invention the tyre is supported for rotation by means engaging externally with the tread thereof, and a further pressure is applied on the beads in opposition to the support means and in the general plane of the tyre. As shown, a vertical cage 4, 5 carries tyre support rollers 1, 2 which are motordriven to rotate the tyre. A foot-pedal 14 actuates a system of linkages to cause two crossmembers 20, 21 to centre the tyre on the support rollers 1, 2, the cross-members disengaging with the tyre on release of the foot-pedal. Two pairs of guide rollers 30, 31 are then caused to engage simultaneously with the upper sector of the tyre by means of a hydraulic ram J operating through a system of levers and linkages 48, 41, 39, 35, 33, and hold the tyre centred on the support rollers. Tyre-spreading means comprising two conical rollers E, E<SP>1</SP> are carried on a swinging assembly hinged to a frame 63 slidably mounted on two vertical columns 60. The swinging assembly comprises two underslung arms 66 supporting a platform 70 and brace-plates 69, 69<SP>1</SP> which carry bearings for two parallel screw-threaded shafts 73, 74. The conical rollers E, E<SP>1</SP> are mounted on screw-threaded blocks 73<SP>1</SP>, 741 carried by the shafts 73, 74 and bearing on the underside of the platform 70 so that rotation of the shafts displaces the blocks thereon. The swinging assembly is normally disposed outside the cage 4, 5 to allow insertion of the tyre, but is actuated by a hydraulic ram K through a lever 99 and a linkage 103 to move into the cage to a position over the beads of the tyre. The frame 63 is then lowered by a hydraulic ram M to engage the rollers E, E<SP>1</SP> with the inside of the tyre walls. A handle 90 operating through a pinion 85 and bevel gears 84, 83, 82 is actuated to cause relative displacement of the conical rollers E, E<SP>1</SP> and thus spread the tyre. Ball-bearing races 77 mounted vertically at the ends of the blocks 731, 741 act as pressure rollers on the inner periphery of the tyre beads. A rotating rasp R is mounted on a support N and is movable into engagement with the tyre tread by means of a screw-jack (not shown). The various hydraulic operating means and the drives for the support rollers and/or the rasp R may be controlled through a single control element to render the machine fully automatic. The conical rollers E may also be power-operated.