SEAT POST

Abstract: A seat post for bicycles and the like adapted to provide a cushioned ride. The seat post (10) comprises an upper post member (13) and a lower post member (14) interconnected for telescopic movement. The upper post member is adapted to support a seat and the lower post member is adapted for connection to a frame member of a bicycle or the like. A spring means (23) acts between the upper and lower post members to resiliently resist downward movement of the upper post member relative to the lower post member. The upper post member (13) has a protrusion (19) extending from the side wall thereof and the lower post member (14) has a slot (21) which is formed in the side wall thereof and which extends longitudinally with respect to the post. A bush (27) of low friction material is positioned between the upper and lower post members. The bush is provided with a lug (29) received in the slot (21). The lug (29) defines a further slot (31) which is aligned with the slot (21) and in which the protrusion (19) is received.

Description: "Seat Post" FIELD OF THE INVENTION THIS INVENTION relates to a seat post for bicycles and other velocipedes and more particularly to a seat post which is adapted to cushion shocks transmitted to a rider. BACKGROUND OF THE INVENTION It is usual for a bicycle to have a seat supported on a bicycle frame by way of a rigid seat post. While this is a simple way of supporting the seat, it does have a disadvantage in that the rigid seat post transmits shocks directly to the seat. With a view to overcoming this disadvantage, there have been proposals for seat posts which provide cushioning between the bicycle frame and the seat. One such proposal is found in US Patent No. 4,182,508 which discloses a seat post which comprises inner and outer post members in telescopic relationship, the outer post member being adapted to be clamped to a bicycle frame and the inner post member being slidable within the outer post member and protruding beyond the upper end of the outer member to permit a bicycle seat to be clamped to it. A spring acts between the inner and outer post members to urge the inner member upwards and resiliently resist downward movement to thereby provide cushioning to the bicycle seat. To limit rotation and axial travel of the inner post member with respect to the outer post member, the inner member is provided with a longitudinally extending slot in its side wall which receives an inwardly protruding key formation on the side wall of the outer member. Although not stated in US Patent No 4,182,508, the inner and outer post members would typically be made of metal as would the key formation on the side wall of the outer member. The inner and outer post members, are: in direct contact and it is apparent that the would, therefore" " , be prone to excessive wear. A possible solution: to' the- apparent problem of wear would be to provide a bush of low friction material between the inner and outer post members _ but this then introduces a further problem in retaining such a bush in position. SUMMARY OF THE INVENTION The present invention seeks to provide a novel seat post which overcomes the above mentioned problem of retaining '.a bush between telescoping inner and outer post members.- In one form the invention resides in a seat' post comprising upper and lower post members interconnected, or telescopic movement, the upper post member being adapted to support a seat and the lower post member being adapted for connection to a frame member of a bicycle or other velocipede, a spring means acting between the .upper and lower post members to resiliently resist downward movement, of the upper post member relative to the lower ' post member, one post member having a protrusion extending from the side wall thereof and the other post member having a first slot formed in the side wall thereof and extending longitudinally with respect to the post, a bush of low friction material positioned between the upper and. lower post members, said bush being provided with a lug received in said first slot, said lug defining a second slot which is aligned with said first slot an in which said protrusion is received. With this arrangement, the lug serves to retain the bush between the two post members. Additionally the lug serves to isolate the protrusion from the post member provided with said first slot. Preferably said lug is shaped and dimensioned to be a neat fit in the slot. For preference the bush is provided with two said lugs in diametrically opposed relation each received in a respective one of two of said first slots, each lug defining a respective one of two of said second slot, each of said second slots receiving a respective one of two of said protrusions. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood by reference to the following description of one specific embodiment thereof as shown in the accompanying drawings in which:- Fig. 1 is a schematic view showing a seat post according to the embodiment mounting a seat post onto a bicycle frame; Fig. 2 is a perspective view of the seat post; Fig. 3 is a front sectional elevational view of the seat post; Fig. 4 is a sectional side elevational view of the seat post; Fig. 5 is a fragmentary side elevational view of a lower post member forming part of the seat post; Fig. 6 is a fragmentary front elevational view of the lower post member with a portion of the post member broken away; Fig. 7 is a side elevational view of a bush within the seat post; and Fig. 8 is a elevational view of two sections which constitute the bush, with a portion of each section cut away to reveal the inner face of the section. DESCRIPTION OF PREFERRED EMBODIMENT! ,.' The embodiment shown in the drawings is directed to a seat post 10 for mounting a seat 11 onto a bicycle 12. The seat post 10 comprises upper and lower post .members 13 and 14 respectively interconnected for telescopic movement. The upper and lower post members are both of tubular metal construction and the upper post member 13 is telescopingly received within the lower post member 14. The upper post member 13 is adapted to receive and support the bicycle seat 11 in usual manner. In this connection, the upper end of the upper post member 13 is provided with a boss 15 to which the bicycle seat 11 can be clamped 1 . - At the lower end of the boss 15 there is provided a circumferential flange 17 to prevent downward movement of the seat beyond the boss 15. The upper post member 13 is received in the lower post member 14 and is retained in such a position by a metal retaining pin 19. The retaining pin extends transversely through the upper post member and is received at its. ends in slots 21 formed in the side wall of the lower post member 14 and aligned with the longitudinal axis of the post. Co-operation between the retaining pin 19 and the slots 21 allows the upper and lower post members to ~ undergo telescopic movement while preventing .relative rotation about an axis parallel to the longitudinal: axis of the seat post. A spring means 23 acts between the upper and lower post member to urge the upper post member towards its uppermost position. With this arrangement, the spring means resiliently resists downward movement of the upper post member and so acts as a cushion for the bicycle seat. The spring means 23 is in the form of two springs 25, 26 operating in series and each having different spring rates. With this arrangement, cushioning can be provided regardless of the weight of a rider. " Specifically, if a lightweight rider is using the bicycle, the spring having the lower spring rate will operate. On the other hand, if a heavy rider is riding the vehicle, both springs will be caused to operate. A cylindrical bush 27 of low friction plastics material is positioned between the telescoping upper and lower post members, as best seen in Figs, of the drawings. The bush 27 is retained within the lower post member by two opposed lugs 29 provided on the bush and received one in each slot 21. The lugs 29 correspond in shape to the slots 21 and so dimensioned as to be a neat fit into the slots. Each lug is itself provided with a slot 31 which is aligned with the slot 21 and in which the ends of the retaining pin 19 are received. With this arrangement, the lugs 29 isolate the ends of the retaining pin 19 from the lower post member. The cylindrical bush is provided with a peripheral flange 33 at its upper end which locates against the upper end of the lower post member 14, as best seen in Figs. 4 and 5 of the drawings. The bush 27 is formed in two longitudinal sections 35, as shown in Fig. 8. Each section 35 has an arcuate outer surface 37 and an arcuate inner surface 39. The inner and outer surfaces are interconnected by longitudinal edges 41. Each section 35 of the bush is tapered to facilitate insertion into the lower post member 14. The nature of the taper is such that the longitudinal edges 41 slope outwardly in the direction towards the lower end of each bush section, as best seen in Fig. 8 of the drawings. With this arrangement, one bush section can be inserted into position in the lower post member 14 and; then the other bush section can be inserted- The taper in each bush section allows the bush section to be manipulated during insertion so that the lug 29 can be located in the respective slot 31 in the lower post member. When the upper post member 13 is also inserted into the lower post member, it serves to push the bush sections outwardly so that the outer surfaces 37 contact the inner face of the lower post member 14. The cylindrical bush facilitates sliding movement .between the upper and lower post members as they undergo telescopic movement and isolates the retaining pin 19 from the lower post member thereby preventing metal to me al contact. The post according to the embodiment is adapted to" be fitted to a bicycle frame in the manner of a conventional- seat post, with a lower post member 14 received and retained in the usual seat post clamping collar on the bicycle frame. When a bicycle fitted with a seat post according to the embodiment is in use, the spring means 23 urges = the upper post member 13 in the upward direction and resiliently resists downward movement of it. In this way, the seat post serves to cushion the rider against shocks and impacts when the bicycle is in operation and provides improved ride comfort. It should be appreciated that the scope of the invention is not limited to the scope of the _ embodiment described. In particular, it should be appreciated that the seat post has application to other forms of velocipedes including tricycles.

Claims: THE CLAIMS defining the invention are as...follows:- 1. A seat post comprising upper and.; lower post memberis interconnected for telescopic movement,, the * upper post member being adapted to support a seat _and the lower: post member being adapted for connection to a frame member.-of a bicycle or other velocipede, a spring means acting between the upper and lower post . members to resiliently resist downward movement of the upper post member relative to the lower post member, one post member having a protrusion extending from the side wall thereof and the other post member having a first slot formed in the side wall thereof and extending longitudinally with. respect to the post, a bush of low friction material positioned between the upper and lower post members, said bush being provided ' with a lug received in said first slot, said lug defining, a second slot which is aligned with said first slot. and. " in which said protrusion is received. 2. A seat post according to claim 1 wherein said lug. is shaped and dimensioned to be a neat fit in the slot. 3. A seat post according to claim 1 or 2 wherein said bush is provided with two said lugs in diametrically opposed relation each received in a respective one of two of said first slots, each lug defining a respective one of two of said second slot, and each of said second slots' receiving a respective one of two of said protrusions.. 4. A seat post according to claim 3 wherein said protrusions comprise the end portions of a transverse-" in provided on said one post member. 5. A seat post according to any one of the preceding claims wherein said bush is provided with a peripheral flange. 6. A seat post according to any one of the preceding claims wherein said bush comprises two longitudinal bush sections. 7. A seat post according to claim 6 wherein said each bush section is tapered to facilitate insertion of the bush into one of the post members. 8. A seat post according to any one of the preceding claims wherein said spring means comprises at least two springs acting in series. 9. A seat post according to any one of the preceding claims wherein said one post member is said upper post member and said other post member is said lower post member. 10. A seat post substantially as herein described with reference to the accompanying drawings.

Inventors: MOULE ANTHONY, MOULE, ANTHONY
Applicants: ROGERSON CHRISTOPHER, ROGERSON, CHRISTOPHER
Application year: 1988
Main classification: B62J1
IPC codes: B62J1