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Patent Searching and Data


Title:
TENSIONING AND LOCKING DEVICE, IN PARTICULAR FOR SNOW CHAINS
Document Type and Number:
WIPO Patent Application WO/2005/095129
Kind Code:
A1
Abstract:
A tensioning and locking device, in particular for snow chains, characterised by comprising: - a casing (2) provided with an aperture (10, 12) for passage of a tie cable (54), - positioned within the casing (2), a reel (14) to which the tie cable is secured, and which is provided with two ring gears (16, 18) with opposing toothing, - two retention pawls (34, 36), each elastically engaging in a corresponding ring gear (16, 18), - an actuator (46) to selectively disengage, against its elastic action, one of the pawls from the corresponding ring gear and enable the reel to rotate in one direction only.

Inventors:
Zanetti, Paolo (Via Cesare Battisti 9, Conegliano, I-31015, IT)
Application Number:
PCT/EP2005/003267
Publication Date:
October 13, 2005
Filing Date:
March 29, 2005
Export Citation:
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Assignee:
AM TEKNOSTAMPI S.P.A. (Via degli Artigiani 7, Crocetta del Montello, I-31035, IT)
Zanetti, Paolo (Via Cesare Battisti 9, Conegliano, I-31015, IT)
International Classes:
B60C27/10; B60P7/08; (IPC1-7): B60C27/10; B60P7/08
Domestic Patent References:
WO2004022363A1
Foreign References:
US20030102065A1
US6109846A
Attorney, Agent or Firm:
Piovesana, Paolo (Via F. Baracca, 5/A, - Venezia Mestre, I-30173, IT)
Download PDF:
Description:
TENSIONING AND LOCKING DEVICE, IN PARTICULAR FOR SNOW CHAINS The present invention relates to a tensioning and locking device, in particular for snow chains. Known tensioning and locking devices for snow chains are connected at two points, namely to one end of the outer chain and to one end of a transverse chain, and are provided with a flexible tie cable wound on a reel and elastically engaging the other end of the outer chain. These devices are generally provided with levers and pushbuttons which, depending on their position, enable the cable to be pulled and its two ends connected together, to ensure chain tensioning and to lock this tensioning configuration. DE 19708756 describes a tensioning and locking device comprising a casing housing a reel for winding the cable and on which a lever-operated toothed pawl engages. This know device has however certain drawbacks, and in particular: - a certain danger during use as there is nothing to prevent the spring from elastically returning the cable, which can strike the user's hands. To this must be added the fact that the lever is located in a position reachable by the cable hook, - it is laborious and difficult to manoeuvre, - poor operational reliability, as the slot along which the lever slides can fill with snow and/or ice which can hence hinder lever movement, - possible accidental operation of the lever projecting from the casing, to cause malfunction, chain slackening and general risk of damage to those parts which come into contact with the slackened chain. An object of the invention is to eliminate these drawbacks by providing a tensioning and locking device which can be easily and comfortably operated. Another object of the invention is to provide a device which enables the degree of chain tensioning to be maintained stable even following settling during vehicle travel. Another object of the invention is to provide a device which is reliable as it is completely sealed against external agents. These and other objects which will be apparent from the ensuing description are attained according to the invention by a tensioning and locking device, in particular for snow chains, as claimed in claim 1. A preferred embodiment of the present invention is described hereinafter by way of non-limiting example, with reference to the accompanying drawing, in which: Figure 1 is an exploded perspective view of the tensioning and locking device of the invention, and Figure 2 is a cross-section therethrough. As can be seen from the figures, the tensioning and locking device of the invention comprises substantially a cylindrical casing 2 closed by a cover 3 by screw means 4, and comprising in correspondence with the lateral surface 6 a slot 8 and an aperture 10 connecting to a channel 12 also closed by the cover 3. The casing houses a reel 14 provided with two ring gears 16, 18 with opposing toothing. Hereinafter in the description, the upper ring gear will be indicated by 16 and the lower ring gear by 18. In the cylindrical cavity 20 of the reel 14 there is inserted a helical spring 22, of which the inner end is fixed into a slot 24 provided in a boss 26 formed on the base of the reel and the outer end is engaged in a cut 28 provided in the inner lateral surface of the reel 14. The facing surfaces of the casing 2 and of the cover 3 comprise seats 30 for holding pins 32 present in retention pawls 34, 36 respectively. The pawl 34 presents a tooth 38 facing the upper ring gear 16 whereas the pawl 36 presents a tooth 40 facing the lower ring gear 18. Two coil springs 42, disposed coaxial to pins 44 present on the facing surfaces of the casing and cover, maintain the teeth 38 and 40 engaged in the ring gears 16 and 18 respectively in the absence of external stresses, as will be apparent hereinafter. A slider indicated overall by 46 is inserted in the slot 8 and comprises an operating knob 48 provided with fins 50 and with an operating member 52 interfering with one or other of the retention pawls, according to the position of the slider 46. The device also comprises a tie cable 54 which is fixed at one end to the reel 14, runs along the channel 12 and is provided at the other end with a ring 56. The casing, the pawl, the reel and the slider can be made of metal, preferably magnesium alloy which presents greater lightness and mechanical strength. All other components can be made of plastic. The device of the invention operates in the following manner: after fixing the ends of the inner chain and laying all the transverse chains to straddle the wheel, the slider 46 is rotated clockwise (with reference to Figure 2) so that the operating member 52 interferes with the retention pawl 36 in the sense of disengaging the tooth 40 from the teeth of the ring gear 18 of the reel 14. At the same time the elastic reaction of the spring 42 causes the tooth 38 of the retention pawl 34 to engage in the ring gear 16 of the reel 14. The cable 54 is then pulled to secure the closure ring 56 to the other end of the chain. This operation is possible as the ring gear 18 is completely disengaged and the passive flank of the teeth of the ring gear 16 can be passed over by the tooth 38 against the elastic reaction of the spring 42. At the same time, if the user loses grip on the cable, its sudden return into the reel interior is prevented as the tooth 38 engages the active flank of the ring gear 16 to hence prevent its clockwise rotation. When the ring 56 has been engaged by the chain, the user rotates the slider clockwise to disengage the tooth 38 of the pawl 34 from the ring gear 16 and enable the elastic reaction of the spring 42 to cause the tooth 40 of the pawl 36 to engage the ring gear 18. Following this operation the elastic reaction of the spring 22 enables the reel 14 to rotate clockwise to hence draw part of the cable into the device such as to tension the chain. It should be noted that when in this configuration the cable cannot be pulled in the direction which would cause it to escape from the casing as the tooth 40 is engaged in the ring gear 18, and consequently prevents its anticlockwise rotation. From the aforegoing it is apparent that the device of the invention presents numerous advantages, and in particular: - it can be easily and comfortably operated, - it enables the degree of tensioning to be maintained stable, - it presents no danger to the user as any accidental elastic return of the cable by the reel is prevented, - it presents a reliable seal against snow or ice as the fins 50 close the slot 8 for any slider position.