BOGIE STRUCTURES, PARTICULARLY FOR LAND VEHICLES
United States Patent 3628808
In a bogie structure the wheel axles are carried by leaf springs secured to the bogie frame, and one or more leaf springs extend throughout the length of the bogie and have their end portions laterally nonrotatably mounted in supports provided on the bogie frame, while the end portion of one leaf spring is movable in its support longitudinally of the bogie.
B60G5/047; B60G11/04; (IPC1-7): B60G11/02; B60G11/04; B60G5/00; B60G5/047; B01g019/00
What I claim and desire to secure by Letters
1. A bogie structure, specially for a road vehicle, comprising at least two wheel-carrying axles connected to a frame for said vehicle by means of leaf springs means, said leaf spring means comprising a first elongated leaf spring having a length greater than the distance between said two axles, first connecting means connecting one end of said first leaf spring to said frame, said leaf spring means also including at least one shorter leaf spring having one end connected to the other end of said first elongated spring by second connecting means, said shorter leaf spring being generally symmetrically located relative to one of said axles, said second connecting means being longitudinally movable relative to said frame, said second connecting means providing a nonturnable connection between said other end of said first spring and said one end of said shorter spring, and third connecting means firmly connecting the other end of said shorter spring to said frame, said spring means being so designed and dimensioned that the bending strain acting on the first spring at a point between the axles is zero for all values of vertical load.
This invention relates to a bogie structure, particularly for land vehicles, in which the wheel axles are carried by leaf springs secured to the vehicle frame. The prerequisite for such a leaf spring arrangement in bogie structures is that the axle loads do not change appreciably even if the wheels are at different levels on an uneven roadway.
There have been suggested several solutions of this problem. One frequently applied solution involves the insertion of a hinge connection between the wheel axles. However, any hinge connection will weaken the structure considerably with regard to the very large and oppositely directed forces which act upon the front and rear axles of the bogie when the vehicle is driven through curves. Besides, in many bogie structures considerable drawbacks are encountered upon braking, since the weight distribution on the axles is heavily dislodged.
To eliminate the drawbacks associated with the previously known leaf spring arrangements in bogie structures in respect of nonuniform pressure distribution on the axles and the uneven weight distribution upon braking, it is suggested according to the present invention to provide one or more elongated leaf springs having a length greater than the distance between the bogie axles, the end portions of said elongated leaf springs being laterally nonrotatably mounted in supports provided on the frame, and at least one end portion of at least one elongated leaf spring being longitudinally movable in a support on said frame. This arrangement is realized by the possibility of dimensioning the spring system in such a way that the bending moments acting upon the elongated spring leaves at a point between the wheel axles theoretically are zero for all values of vertical load on the bogie as long as the roadway is plane. The additional stresses arising on the leaf springs between the wheel axles when the vehicle is driven on uneven roads are small and insignificant. Moreover, the structure suggested by the present invention implies a reduced wear and a smaller number of lubricating points. Also, the lateral forces are transmitted to said supports on the vehicle frame by reason of the lateral rigidity of the leaf springs.
The invention will be more fully described in the following with reference to the accompanying drawings in which:
FIG. 1 is a side view of an arrangement according to the invention as applied to a two-axle bogie;
FIG. 2 shows an arrangement similar to FIG. 1 but applied to a three-axle bogie;
FIG. 3 shows various types of additional springs suited for being combined with the longitudinal leaf springs.
In the two-axle bogie shown in FIG. 1 lengthened leaf springs 3 extend beyond the two axles, one end of said leaf springs being fastened at one end of the bogie in spring brackets 6 secured to the frame 1 and the other end being nonrotatably but longitudinally slidably disposed in a fork-shaped spring bracket 7 at the other end of the bogie. The longitudinal forces are thus wholly taken up by the spring bracket 6. To reduce the friction in the fork-shaped spring bracket 7, a packing 8 for instance of neoprene may be inserted between the leaf spring and the spring bracket 7. At the front end of the lengthened leaf spring, which is fixedly anchored in the spring bracket 6, a lower additional spring 5 is fixedly connected to the leaf spring 3. At the rear end of the lengthened spring a short leaf spring 4 having a lower additional spring 5 is connected to the lengthened spring 3 by means of a collar 18, for example a piece of flat iron bent around and loosely embracing both springs 3,4 so that a lateral displacement is prevented but not a shift in the longitudinal direction. The other inwardly facing end of the short leaf spring 4 is attached to a spring bracket 10 which is fixedly mounted on an anchorage 9 secured to the bogie frame 1.
FIG. 2 shows the invention applied to a three-axle bogie. The structure is essentially the same, but so designed that the entire bogie is caused to follow the frame 2 by the provision of a strong pin 14 extending through a forked-shaped bracket 13 with a certain clearance to guide said long spring 3 longitudinally in relation to said spring bracket 13. The spring brackets 16 for the additional springs at the ends of the lengthened springs 3 correspond to the spring bracket 6 in FIG. 1, while the spring brackets 15 corresponds to the spring bracket 7 in FIG. 1 to allow a longitudinal movement also in the latter case. The undersides of the spring brackets 13 and 15 are arched to permit a rocking movement of the springs. An additional spring 5 is arranged at the intermediary axle and connected to it via spacing means 17.
In the bogie structures according to both FIG. 1 and FIG. 2 upper additional springs 5' are also provided at the points where the longitudinal leaf spring is movably mounted.
The additional springs 5, 5' may be designed as desired, for instance as shown in FIG. 3. 20 designates an ordinary leaf spring, and 21 a rigid leaf spring having a single thick leaf, while 22 is a leaf of corresponding thickness which in the unloaded state has a clearance 19 to provide progressive deflection.
When a vehicle equipped with a bogie structure according to FIG. 1 is braked the weight distribution will theoretically change merely to an insignificant extent, and with a bogie structure according to FIG. 2 the weight distribution will not change at all.