GB2111002A

GB2111002A - Bicycle steering head assemblies

Info

Publication number: GB2111002A
Application number: GB08229157A
Authority: GB
Inventors: Hermanus Laurentius Mar Postma
Original assignee: SKF Industrial Trading and Development Co BV
Current assignee: SKF Industrial Trading and Development Co BV
Priority date: 1981-10-12
Filing date: 1982-10-12
Publication date: 1983-06-29
Also published as: BE894549A; DE8227814U1; NL8104629A; GB2111002B; IT8223139V0; FR2514315B3; IT1153903B; FR2514315A3; IT8223693A0; JPS5870985U; JPS6320630Y2

Abstract

A steering head (11) houses co- axially a column (12) which supports at the lower end the front-wheel fork and at the upper end receives the handlebar, the column being journalled by two rolling bearings, (148, 18) each of which comprises a set of elements (14''', 18''') rolling on inner and outer races (14', 18', 14'', 18''), the elements being spaced by a cage (not shown). Confining members (15, 19, 17, 20) in contact with the inner and outer races respectively of the rolling bearings are fixed to the column 12 (members 15, 20) and the steering head 11 (members 17, 19). The member 20 cooperates with an outwardly bent portion 21 of the tube 12 to act as a locking member. Figure 1 shows a conventional steering head assembly. <IMAGE>

Description

SPECIFICATION Head tube for a bicycle The invention concerns a head tube for a bicycle, comprising an outer tubular piece which may be attached to the frame ofthe bicycle and an inner tubular piece, situated co-axially therein, to which at the lower end may be attached the front-wheel fork of the bicycle and which at the upper end is capable of receiving the handlebar of the bicycle, while between these tubular pieces, near the ends thereof, are situated two rolling bearings, each of which comprises a set of rolling elements and a confining member communicating with the inner tubular piece and the outer tubular piece respectively, the uppermost confining member, communicating with the inner tubular piece, being capable of co-operating with a locking member for securing the inner tubular piece.

In a known head tube the rolling elements of each bearing, in the form of balls, are simply confined between a dish connected with the outer tubular piece and a cone connected with the inner tubular piece, so that the balls may roll against one another, as a result of which the bearing wears relatively rapidly. In addition, assembly of such a bearing is relatively difficult, since during assembly the balls may fall out.

Moreover, it is necessary that the locking member be designed as an adjusting member consisting of a separate annular member, provided with internal screw thread, which is screwed against the uppermost cone on the uppermost part of the inner tubular member, provided with external screw thread. However, if the adjusting member is screwed on too tightly, the balls may receive too great a load, which may likewise result in great wear.

Hitherto it was believed that bearings having a dish and a cone were necessary for the bearing of a head tube, because it was only by these means that good centering of the innermost and outermost tubular pieces with respect to one another was possible.

Pursuant to the invention, it has been found that all the above-mentioned advantages of the known head tube are eliminated when each bearing is formed by a premanufactured rolling - bearing unit, for example a ball bearing, having an inner race, an outer race, a plurality of rolling elements arranged to roll on the races, and a cage spacing the rolling elements from each other, and the confining members are in contact with the inner and outer races respectively of the rolling bearing. In addition, no centering problems appear when the confining members are made accurately to size, which preferably may be done in a simple and economical fashion by forming these members by pressing.

In this way, pursuant to the invention there is obtained a head tube for a bicycle where the rolling elements are no longer capable of rolling against one another owing to the fact that they are separated from one another by a cage; no adjusting member is necessary, so that the rolling elements may no longer be exposed to excessively great loads; and wear is considerably reduced, while assembly is relatively simple and the total costs of the head tube itself are lower than those of the known head tube.

The lowermost confining member connected with the inner tubular piece may advantageously be formed by an annular thickening of or on the inner tubular piece.

The locking member may form a whole with the corresponding confining member, where the locking member may be secured by a bend outward of the upper end of the inner tubular piece.

An embodiment of the invention will now be described with reference to the accompanying drawing wherein in longitudinal cross section Figure 1, on the left hand side shows the known head tube, and Figure 2, on the right hand side shows a head tube according to the invention.

The known head tube, as shown in Figure 1 on the left hand side of the drawing, consists of an outer tubular piece or forks frame tube 1 and an inner tubular piece or forks column 2, situated therein, which at the lower end is attached to the plate 3 of a front-wheel fork of a bicycle, not further represented.

At the lower end is fitted a bearing consisting of a set of balls 4 which are situated between a dish 5 and a cone 6. At the upper end is present a bearing consisting of a set of balls 7 which are situated between a dish 8 and a cone 9. In addition, on the upper end of the inner tubular piece 2, provided with screw thread, is screwed an annular adjusting member 10 which is screwed tight against the cone 9.

As shown in Figure 2 on the right hand side of the drawing, a head tube according to the invention, comprises an outer tubular piece or forks frame tube 11 and an inner tubular piece or forks column 12, situated therein, which at the lower end is attached to the plate 13 of the front-wheel fork of the bicycle.

At the lower end is mounted a ball bearing 14 consisting of an inner race 14' and an outer race 14" and a set of balls 14"' situated between these races, which balls are separated from one another by a cage, not shown. The inner race 14' is in contact with an annular thickening 15 at the lower end of the inner tubular piece 12, while a supporting ring 16 is present. The outer race 14' is in contact with a confining member 17 which is manufactured by a pressing process.

Nearthe upper end is mounted a ball bearing 18 consisting of an inner race 18', an outer race 18" and a set of balls 18"' separated from one another by a cage, not shown. The inner race 18' is in contact with a confining member 19, while the outer race 18" is in contact with a confining member 20, the two confining members 19 and 20 being manufactured by means of a pressing process. The confining member 20 is fixed with respect to the inner tubular piece 12 by the upper end 21 of the inner tubular member being bent outward, as represented in the drawing.

The annular thickening 15 of the inner tubular piece 12 may be replaced by a ring secured to the inner tubular piece.

Claims

1. Head tube for a bicycle, comprising an outer tubular piece which may be attached to the frame of a bicycle and an inner tubular piece, situated coaxially therein, to which at the lower end may be attached the front-wheel fork of the bicycle and which at the upper end is capable of receiving the handlebar of the bicycle, while between these tubular pieces, nearthe ends thereof, are situated two rolling bearings, each of which comprises a set of rolling elements and a confining member communicating with the inner tubular piece and the outer tubular piece prespectively, the uppermost confining member, communicating with the inner tubular piece, being capable of co-operating with a locking member for securing the inner tubular piece, wherein each bearing is formed buy a rolling-bearing unit having an inner race, an outer race, a plurality of rolling elements arranged to roll on the races, and a cage spacing the rolling elements from each other, the confining members being in contact with the inner and outer races respectively of the rolling bearing.

2. Head tube according to Claim 1, wherein the confining members consist of pieces which are formed by pressing.

3. Head tube according to Claim 1 or 2, wherein the lowermost confining member, connected with the inner tubular piece, is formed by an annular thickening of or on the inner tubular piece.

4. Head tube according to one of Claims 1 to 3, wherein the securing member forms a whole with the corresponding confining member.

5. Head tube according to Claim 4, wherein the securing member is secured by a bend outward of the upper end of the inner tubular piece.

6. Head tube for a bicycle substantially as herein described with reference to and as shown in Figure 2 of the accompanying drawing.