The present invention concerns a telescopic hydro-pneumatic fork, specifically for mountain-bikes, trail-bikes, other bicycles or mopeds, equipped with rapid lock and release control of the extension stroke, to adapt the fork to the various operating conditions of the means of transport and to the various needs of the user.

When using the aforementioned competition bicycles equipped with a shock absorbing telescopic front fork, it is desirable to stiffen the fork in extension when the bicycle travels on an uphill route, to neutralise the pitching movement which brings the user to an off-balanced position, often close to falling over, and which does not permit the user to express his physical strength to its utmost. When the bicycle travels on an uphill route, it is also desirable that the height of the front fork is adequately reduced with respect to the normal extension position of the fork, in such a manner as to move the barycentre of the bicycle/user forward.

To solve this problem, telescopic forks are currently equipped with an adjustment device which allows them to be stiffened in the course of the extension, with an operation that is, however, complicated since it requires to screw and unscrew a regulator.

The present invention proposes a solution with which the lock and release operation of the fork can be executed with a rapid ON-OFF control, which provides for the use of a valve of suitable type, preferably of rotating type, in the internal hydraulic circuit of the fork.

Major characteristics of the invention, together with its advantages, will appear more evident from the following description of a preferred embodiment, shown solely as an example, and not in a limiting sense, in the figures contained in the enclosed drawings, in which: -Figures 1 and 2 are a longitudinal cross-section of a leg of a telescopic fork

with visible parts and with the valve device in rest and locked position, respectively; -Figures 3 and 4 are an enlarged view of the valve device according to the present invention, in the condition of figure 1 and figure 2, respectively; -Figure 5 is a longitudinal cross-section with visible parts of the top of the leg of the fork with the control for the aforesaid device; -Figure 6 is an enlarged detailed section of the end of the stroke means of the control, as per figure 5; -Figure 7 is a perspective view of the top of the fork leg, with its various controls or regulators; -Figure 8 is a front view of a telescopic fork according to the present invention.

In Figures 1 and 2 the sheath of the leg of a fork indicated with (1) is equipped below with an appendage (101) with forked or ringed shape, for the connection to the axis of the front wheel of the bicycle and, if necessary, equipped with further appendages (201) to support a pincer for a disk brake.

On the upper side the sheath (1) carries other appendages of known type, referred to hereinafter, for the connection of a small arch to the sheath of the other leg of the fork and ends with a widened part (301) with a seat (2) with diameter greater than the internal cavity of the sheath. A ring collar (103) of a thin bushing (3) made with a material with low friction coefficient and high resistance to wear rests on the bottom of the seat. A washer (4) of suitable material rests on the collar (103) of the bushing, topped with a sealing ring (5) which is locked into the seat (2) by means of an elastic ring (6). The seat (2) is designed to receive an embedded end ring (7) with its internal parts functioning as dust scraper.

The shaft (8) with round section is mounted and axially slides with lateral seal by means of the bushing (3) in the cavity of the sheath (1), with its upper end connected to the crossbar-see hereinafter-joined to the shaft of a telescopic system equal and parallel to the one in question, and which has the steering axle. The lower end of the shaft (8) is internally equipped with a recessed ring, which houses and axially blocks with the elastic ring (10) the

ring collar of a bell (11) open above and traversed through the clearance 12 by a small cylindrical tube or cartridge (13) with round section, made of suitable light alloy, equipped in a single piece on the bottom of an axial threaded straight shank (113), screwed into a cap nut (14) which is in turn equipped with an axial centring shaft (114), which exactly engages with lateral seal by means of a gasket (15) into an opening made in the centre of the elevated end plate (401) of the sheath (1). The sheath (1) is open on the lower end to permit access to the end plate and the nut (14). The cartridge (13) is closed on top by a plug (16) laterally equipped with a recessed ring in which a corresponding lateral portion of the cartridge is pushed down, as indicated with (17). An open elastic ring (18) is lodged in the ring depression (17), on which a cup (19) is placed and slightly flanged below. The upper end of a helical cyfindricaf spring (20) rests against the lower end of the small cup, resting its other end against the summit of the lower bell (11) of the stem (8) when this is in its maximum extension position, as shown in figure 1. At least one antagonist helical cylindrical spring (21) rests on the upper end of the cup (19), engaging the stem (8) for its entire length and held in place by a plug (22) equipped with means to pre-load the spring which has the function of stressing the stem in, extension and absorbing the compression stresses to which the telescopic. system is placed due to rough terrain. Prior to mounting the plug (22), which, with its externally threaded tank (122) is screwed to a corresponding internally. threaded part of the upper end of the sheath (1), the proper quantity of a suitable liquid is added in the sheath, preferably reaching right above the cup (19), passing in the clearance that exists between the cup and the lateral inner surface of the stem (8), for example up to the line indicated with (23) in figure 1. The liquid completely fills the free chamber C of the sheath (1) and the, cartridge (13) into which it flows through a lower opening (24) with proper section. Some air remains in the upper chamber D which is not engaged by the liquid, which is compressed during the contraction of the fork leg and creates an elasticity which is added to that in the spring (21). The plug (22) is equipped with a gasket (25) to set a connection seal on the stem (figure 5) and is axially drilled for the passage of

the tapered part of the upper end (126), with a lateral holding gasket (27) of a screw (26) which is held ; axially on site by an elastic ring (28) and which may be controlled by meansof an external handle (29). On the screw (26) a female nut (30) externally equipped with teeth (130) is threaded, which engage with the corresponding longitudinal recess (31) of the lateral surface of the axial cavity of the plug (22), in which the nut and screw are lodged. On the lower end of the female nut (30), the upper end of the antagonistic spring (21) rests with the interposition of a centring cup (32). By acting on the handle (29) the screw (26) may be rotated to determine the corresponding axial movement upwards or downwards of the female nut (30) to pre-load the spring (21), as desired.

Figure 5 also shows that the adjustment screw (26) is equipped with an axial cavity divided into three lengths with decreasing diameter towards the top, in which the lower part (33) is threaded and has the end of a pipe (35) screwed into it and axially locked by means of a lock nut (34), extending downwards (see figure 3) and passing through an axial opening in the plug (16) equipped with a lateral seal gasket (36) and entering the cartridge (13) where it ends with an externally threaded end (37) on which the head of a glass-shaped body (38) is screwed (see figure 3), whose base is tapered and externally threaded for the axial screwing of a piston (39) which, with an external gasket (40), slides in a lateral connection in the cartridge (13). The piston (39) is equipped in parallel position to its axis with a variety of openings (41) and on the piston a means of interception (42,142) is mounted as a covering for the openings, pushed downwards by a spring (43) and formed for example by an upper steel disk (42) and by at least an underlying disk in rubberised cloth acting as washer. It is understood that the seal part (142) may also be vulcanised onto part (42). The piston (39-40) divides the internal space of the cartridge (13) into two chambers A and B and the means of interception (42, 142) are such as to permit the free passage of the liquid from the lower chamber A to the upper chamber B through the holes (41), when the fork works in contraction and to block the passage of the liquid through the openings (41) when the fork works in extension and the liquid should pass

from chamber B to chamber A.

Figure 3 also shows that the glass-shaped body (38) is equipped with an axial cavity (44) which communicates with the axial cavity of the pipe (35), which ends at the bottom with a widened section in which the widened end (145) of a rod (45) which crosses the entire length of the pipe (35) is lodged and turns, without the possibility of axial movement, co-operating with means of the lateral seal (46) (figure 5), passing axially through the screw (26) with which it co-operates with means of lateral seal (47) and exiting from the screw with a section designed to attach a control handle (48) (see hereinafter). On the widened part (145) of the rod (45) (figure 3), which acts as rotating slide valve, as hereinafter defined, a blind hole (49) is created axially, which is in constant communication with the hole (44) and a radial hole (50) is created, which is in constant communication with the hole (59) and according to the angular position of the slide valve (145) can or cannot communicate with a lateral hole (51) of the pipe (35), as illustrated in figure 3 or in figure 4, respectively. When the bicycle is in an horizontal route or a downgrade, the fork is used in the condition shown in figures 1 and 3, with the hole (50) communicating with the hole (51), in such a manner that the piston (39) can axially move in both directions within the cartridge (13) and in such a manner that the fork can contract and extend. When the bicycle is on an uphill route, the assembly (45,145) rotates into the condition shown in figure 4, with the hole (50) isolated from the hole (51), in such a manner that the piston (39-40) may move downwards following to a compression stress of the fork and in such a manner that it remains in the position reached from time to time, impeding the extension movement of the fork.

The applicant is the owner of patent applications used to realise a front telescopic suspension for bicycles, as schematically shown in figure 8, in which the hub M of the wheel has an elevated resistance to mechanical stresses and may be firmly connected to the lower connections (101) of the sheaths of two legs G1 and G2 of the fork, while the upper ends of the sheaths are equipped with appendages (501) with which they may be firmly connected by means of an arch-shaped structure A. Also the upper ends of

the stem (8) are firmly connected through the cross brace T which carries the axis S of the steering column. This technology allows for the creation of the legs G1 and G2 of the fork, housing cartridges (13) having different functional characteristics, to meet with the different operating needs of the fork. For example, the leg G1 of the fork may house a cartridge (13) containing the lock and release device with rotating slide valve illustrated in the present patent application, which provides for the adjustment handle (29) for the antagonistic spring and the lock and release handle (48) for the extension on the top of the leg. The other leg G2 of the same fork may house a cartridge (13) containing devices for the interception of the hydraulic flow, of the type described for example, in the Italian patent number 1,287,600 in the applicant's name, which provides for an adjustment handle (29) for the antagonistic spring and a handle (48') or other means to regulate the degree of locking of the fork during the extension movement on the top of the fork. To lock or release the extension of the fork, the user must act on a single control, which may in the future be controlled at a distance by means of a flexible cable, or by means of a hydraulic servo control or through an electro-mechanical servo control. The leg G2 of the fork may otherwise be produced in a manner identical to leg G1, with the difference that the handle (48') connected to a rotating slide valve identical to the one shown in Figures 3 and 4 can be designed to remain stable also in intermediate and end positions to divide in parts the light passing through the opening (51) (figure 3) and to create in this way the adjustment of the degree of braking in the extension of the fork.

Preferably, the handle (48) has a smaller diameter than the handle (29) so that the two handles may be selectively grasped by the user's hand. The handle (48) is placed at a short distance from the underlying handle (29), almost touching it, and is equipped in parallel to its axis with a blind opening (54) (figures 5,6,7) open towards the bottom, which houses a pin (55) pushed towards the bottom by a spring (56) and which with its lower rounded head slides in a track (57) with circular section located in a recess on the upper face of the handle (29) and terminates with end areas (157) with greater depth, in which the pin in inserted with a click and stopped. To switch

the rod (45) in the angular lock and release position shown in figures 3 and 4, it is necessary to rotate the handle (48) in one direction or the other by the angular movement permitted by the arched track (57). If the handle (48) is not used as an OFF-ON control, but as a regulator to choke the opening (51), as previously noted with reference to figure 7, the arched track (57) may be equipped with equidistant depressions (257) (figure 6) into which the small pin clicks to stabilise the handle in the intermediate positions. In this case the handle (48) could be usefully equipped with a reference index (52) (figure 7), which co-operates with a graduated scale (53) obtained on the upper face of the underlying adjustment handle (29) of the antagonistic spring and furnished with the indications ON and OFF at its opposite ends. It is not excluded that both the handles (48,48') of the two legs of the fork may be provided with the possibility of stabilisation in an intermediate position with respect to the ends of the stroke, in such a manner that the user may use the lock and release control for the extension of either one of the two handles placed on the right or left side of the fork, according to whether he is right or left-handed.

It is understood that the lock and release device according to the present invention is protected even if mounted on a telescopic system differing from the one illustrated in figures 1 and 2. It is also understood that the description refers to a preferred form of manufacture of the invention, to which numerous variations and modification may be made, above all during the construction phase, without abandoning the information principle of the invention, as described above and illustrated in the three attached drawings and following claims. In the claims the references in parentheses are solely of indicative nature and do not limit the area of protection of the claims.