Patent GB-1402126-A (GB)
Title: Motion retarding device
IPC: F16H35/12
Filed: 1972-11-14
Abstract: 1402126 External brakes; rotary shoes; retarding toys H K BROSS 14 Nov 1972 [17 Nov 1971] 52608/72 Heading F2E [Also in Division A6] A device such as a toy includes a retarding element formed by an elastomeric or viscoelastic body whose kinetic coefficient of friction varies directly as the sliding velocity over at least a portion of the curve representing kinetic coefficient of friction versus velocity, a counterelement such as an axle or a wheel-engaging surface in contact with the retarding element, and means for maintaining, within the range corresponding to the above-mentioned portion of the curve, the relative velocity between the retarding element and the counter element when at least one of the elements is subject to a force. Preferably the static coefficient of friction of the elastomeric or visco-elastic body is at least 0À5 and preferably greater than 1. In Figs. 2, 3, a toy vehicle has a traction rubber band 5 looped through a running wheel 3; on moving the toy along a surface in one direction the band 5 becomes wrapped around the wheel spindle 4 until a locking element 9 moved transversely by the band engages a projection 7 in wheel 3. The retarding element is a pair of elastomeric bearing bushes 10 having apertures smaller than the cross-section of spindle 4, to maintain the velocity of the counter element-the spindle 4-within the prescribed limits when the toy is released to be driven by the band 5. Bushes 10 are preferably of yieldable polyvinyl chloride or rubber. When the tension of band 5 is greatest, (fully wound), the contact pressure between spindle 4 and bushes 10 is greatest, so the "driven" velocity is approximately constant.  In Fig. 5 (not shown) the wheel spindle of a toy driven by a clockwork motor extends through an orifice of smaller cross-section in a disc forming the retarding element and fixed to the motor housing. In Figs. 6a to 6c (not shown) the spindle of a rubber-band-driven toy has an elastomeric retarding element in one position, and a device for producing normal friction in another position, the latter consisting of a plate with an orifice from which radiate slits to produce "springy" contact with the spindle. The toy in Figs. 7a, b is held in contact with a magnetizable surface 43 by axial magnetization of a roller 38 and descends by gravity. The ring is supported on a fixed spindle 39 by the discs 40, 41, one of which consists of an elastomeric retarding element and the other a spring metal disc with a slit. Rotation is ensured by a sheath 42. Further resistance is afforded by contact at 45. In Fig. 10 a toy 57 is driven along a base 59 by a weight 60. The rolling element 58 is retarded in accordance with the invention by an elastomeric retarding element, and optionally by a further friction element. In Fig. 12a a drive unit 72 provided with an elastomeric retarding element 74 is pushed into a toy vehicle 71, compressing a wavy spring 73. On release of the drive unit, the retarding element 74 first encounters a constriction 75 as the spring expands, this constriction forming the "counter element". Thereafter, the drive unit is projected rapidly outwards, driving the vehicle by reaction. In Fig. 13, the tipper 77 of a tipping lorry 76 has a surface 83, acting as the counter element, engaging under pressure a cushion 84 of elastomeric material acting as the retarding element. When the tipper is released by bolt 82 and raised by spring 80, the tipping motion is so slow as to resemble that of a full-size lorry. The velocity range for devices according to the invention may be from one hundredth of a millimetre to a few millimetres (less than 20) per second. A toy or device may stop and move at intervals, automatically. The retardation may be made variable to permit different speeds to be attained.