Wheel suspension system for tracked vehicles

Abstract: The invention relates to a suspension system for a tracked vehicle of the type comprising support wheels (12) arranged along opposite sides of the vehicle for bearing against the inside of a respective endless drive track, where the support wheels (12) are rotatably mounted at an outer end of a respective pendulum arm (14). The pendulum arms (14) for each pair of opposite support wheels (12) are interconnected by means of a first torsion spring element (18) in the form of a torsion bar. The central portion of the torsion bar (18) is connected in a rotationally fixed manner to a surrounding, torque-transmitting tubular element (22). According to the invention, a second torsion spring element (26) in the form of a rubber bushing is coupled in series to the torsion bar (18) so as to take up, at the same time as and together with the latter, the torque exerted on the pendulum arms (14).

Description: The present invention relates to a suspension system for a tracked vehicle according to the preamble of claim 1, as known from DE-C-968975. In the known suspension system of this type, the torsion bar alone takes up the entire suspension movement of the pendulum arms, which results in above all a limited possible angular capacity of the suspension system. A primary object of the present invention is to develop the abovementioned known suspension system in order to prevent overtwisting of the torsion bar in extreme cases. According to the invention there is provided a suspension system with the features of claim 1; thus in particular complementary engagement members are arranged on the outside of the bearing sleeve of the pendulum arms and on the inside of the end portion surrounding this of the tubular element, which members are designed to allow a predetermined, limited free rotation movement of the bearing sleeve relative to the end portion of the tubular element and, in the event of this free relative rotation movement being exceeded, to be brought into engagement with one another, the pendulum arm short-circuiting the torque force directly to the rubber bushing. Further features of the suspension system according to the invention are defined in the patent claims which follow and are described in greater detail below with reference to the appended drawings, in which: Fig. 1 is a perspective view of a support wheel mounting for a tracked vehicle with a suspension system according to the present invention; Fig. 2 is a sectioned side view of a part of a pendulum arm mounting in one side of a tracked vehicle body, which shows torsion elements coupled in series according to the invention; Fig. 3 shows in perspective view an outer bushing sleeve of the rubber bushing which is anchored on an end portion of a torque-transmitting tubular element; Fig. 4 shows an anchoring ring for preventing rotation of the outer sleeve of the rubber bushing; Fig. 5 shows a pendulum arm in perspective with engagement members on the outside of its bearing sleeve part, and Fig. 6 is a diagrammatic cross-sectional view along the line VI-VI in Fig. 2 but with the support sleeve omitted. In Fig. 1, 10 designates generally a wheel mounting for a pair of support wheels 12 for a tracked vehicle (not shown), the wheel mounting 10 comprising a suspension system according to the present invention. A tracked vehicle usually comprises a number of support wheel mountings 10 positioned one following another along the vehicle, the support wheels 12 on each side of the vehicle bearing against the inside of the lower strand of a respective endless drive track. Each wheel mounting 10 comprises a pendulum arm 14 for each support wheel 12, the latter being rotatably mounted at one (the outer) end of the pendulum arm 14. As shown in Fig. 2, the inner end of each pendulum arm 14 has an axially inwardly directed bearing sleeve 16 and is firmly connected, by means of a splined joint 17 and a screw joint 20, to a respective end of a first spring element in the form of a torsion bar 18. The torsion bar 18 therefore extends across the longitudinal extent of the vehicle and interconnects the pendulum arms 14. A central portion (not shown) of the torsion bar 18 is connected in a rotationally fixed manner via a splined joint to a torque-transmitting tubular element 22 which surrounds the torsion bar 18 and the end portions of which surround the bearing sleeves 16 of the pendulum arms 14. The bearing sleeves 16 are mounted on the inside of the tube ends via a pair of sliding bearings 24. A second torsion element in the form of a rubber bushing 26 is vulcanized firmly on the outside of each end portion of the tubular element 22. An outer bushing sleeve 28 is vulcanized firmly on the outside of the rubber bushing 26 and is supported in a support sleeve 30 with an anchoring flange 32 for fastening the entire wheel mounting 10 in the two opposite sides of the tracked vehicle. The outer bushing sleeve 28 is provided with rotation-preventing engagement members in the form of teeth or tongues 34 on one end edge (Fig. 3), which are arranged so as to engage with recesses 36 in an anchoring ring 38 (Fig. 4) which is to be mounted firmly against the inside of a side wall 40 of the vehicle body (Fig. 2) by means of bolted joints (not shown) which connect the fastening flange 32 to the anchoring ring 38. The anchoring ring 38 may be split or have a recess 42 (Fig. 4) so as to make possible slipping-on over the tubular element 22 before installation of the wheel mounting 10 in the vehicle. In the suspension system according to the invention described above, two torsion springs (the torsion bar 18 and the rubber bushing 26) are therefore coupled in series with one another, the torsion bar 18 and the rubber bushing 26 being designed so as each to take up roughly half the twisting that is caused by the pendulum arms 14 during normal deflection movements (upward deflection). In order to prevent excessive twisting of the torsion bar 18 occurring in the event of, for example, a forceful deflection movement of the pendulum arms 14, engagement members are arranged - in a portion between the axially separate sliding bearings 24 - between the bearing sleeve 16 of the pendulum arm 14 and the respective end portion of the tubular element 22, which members are designed to allow a predetermined, limited free rotation movement of the bearing sleeve 16 relative to the end portion of the tubular element 22 and, in the event of this free relative rotation movement of the bearing sleeve 16 being exceeded, to be brought into engagement with one another so as thus to "short-circuit" the torque transmission from the pendulum arm 14 directly to the rubber bushing 26 which then takes up all the excess torque. As shown in Figs 5 and 6, these engagement members can take the form of a number of axial ribs 44 which are separate in the circumferential direction and formed between wide grooves 46 on the outside of the bearing sleeve 16 and of corresponding axial, inwardly projecting ribs 48 formed between wide grooves 50 on the inside of the end portions of the tubular element 22 (Fig. 6), the ribs 44 on the bearing sleeve 16 being capable of freely moving an angular distance corresponding to the distance between two opposite radial side surfaces of two adjacent ribs 48 on the tube ends before the ribs 44 come into contact with the ribs 48 and transmit the excess torque to the rubber bushing 26. In the suspension system according to the invention, the tubular element 22 therefore connects the two rubber bushings 26 on the left and the right side of the tracked vehicle. In the event that the support wheels do not deflect at the same time, a corresponding blocking of the twisting of the torsion bar 18 can take place on one side, in which case it is possible for excess torque from one support wheel to be distributed to both rubber bushings 26 via the torque-transmitting tubular element 22, the characteristic torsion (1-2°) of which is negligible in this connection. The suspension system according to the invention provides a very great angular capacity at the same time as it makes possible symmetry of the track sets of the vehicle and very low transmission of bending moment to the side of the vehicle. The rubber bushings eliminate any minor errors of geometry and provide a certain degree of vibration insulation.

Claims: Suspension system for a tracked vehicle of the type comprising support wheels (12) arranged along opposite sides of the vehicle for bearing against the inside of a respective endless drive track, where the support wheels (12) are rotatably mounted at an outer end of a respective pendulum arm (14) which, at its inner end, is limitedly pivotably mounted in the side of the vehicle body, and where the pendulum arms (14) for each pair of opposite support wheels (12) are interconnected by means of a first suspension element (18) in the form of a torsion bar which extends across the longitudinal extent of the vehicle and coaxially with the pivoting axis of the pendulum arms (14), a central portion of the torsion bar (18) being connected in a rotationally fixed manner to a surrounding, elongate tubular element (22), one end portion of which coaxially surrounds and supports a bearing sleeve (16) connected to one pendulum arm (14) and the other end portion of which coaxially surrounds and supports a bearing sleeve (16) connected to the other, opposite pendulum arm (14), a rubber bushing being mounted on the outside of each end portion of the tubular element (22) and which torsion element in turn is surrounded by and firmly connected to an outer bushing sleeve (28) designed to be fixed firmly in the side of the vehicle body, characterized in that each rubber bushing is mounted firmly on the tubular element (22) to form a second torsion element (26) and in that complementary engagement members (44, 48; 46, 50) are arranged on the outside of the bearing sleeve (16) of the pendulum arms (14) and on the inside of the end portion surrounding this of the tubular element (22), which members are designed to allow a predetermined, limited free rotation movement of the bearing sleeve (16) relative to the end portion of the tubular element (22) and, in the event of this free relative rotation movement being exceeded, to be brought into engagement with one another to prevent overtwisting of the torsion bar (18). Suspension system according to Claim 1, characterized in that the engagement members comprise, in one part, axial grooves (46, 50) and, in the other part, ribs (44, 48) engaging in these grooves, the ribs (44, 48) having a smaller width than the grooves (46, 50). Suspension system according to Claim 1 or 2, characterized in that the torsion bar (18) is connected in a rotationally fixed manner to the central portion of the tubular element (22) via a splined joint. Suspension system according to any one of Claims 1-3, characterized in that each outer bushing sleeve (28) is supported by a support sleeve (30) with a fastening flange (32) for fixing the entire support wheel mounting (10) in associated stays (38) in the sides of the vehicle body. Suspension system according to Claim 4, characterized in that each outer bushing sleeve (28) has a number of axially directed tongues (34) for rotation-preventing locking engagement with corresponding recesses (36) in the stay (38) or vice versa. Suspension system according to any one of Claims 1-5, characterized in that the bearing sleeves (16) of the pendulum arms (14) are mounted in the end portions of the tubular element (22) via sliding bearings (24). Suspension system according to any one of Claims 1-6, characterized in that the rubber bushings (26) are vulcanized firmly on the end portions of the tubular element (22) and in the outer sleeves (28). Suspension system according to any one of Claims 1-7, characterized in that the rubber bushings (26) for each support wheel pair and the torsion bar (18) are dimensioned so as each to take up roughly half the relevant twisting. Suspension system according to any one of Claims 1-8, characterized in that the two rubber bushings (26) for each support wheel pair are designed to be mounted on the outside of the respective vehicle body side (40).

Inventors: FALK ALFONS, FALK, ALFONS
Applicants: LAND SYSTEMS HAEGGLUNDS AKTIEB, LAND SYSTEMS HAEGGLUNDS AKTIEBOLAG
Application year: 1999
Main classification: B62D55
IPC codes: B60G21, B62D55