Device for automatically lowering and load-dependent raising a lift axle

Abstract

Device (4) for a motor vehicle or a motor vehicle trailer (50) with a tilting loading platform (8), comprising - a locking device (47) for releasably locking the front section of the loading platform (8) to a frame (9, 11) of a motor vehicle or to a drawbar (52) of a motor vehicle trailer (50), wherein the locking device (47) comprises a control shaft (53) oriented perpendicular to the longitudinal axis of the drawbar (52) or of the motor vehicle, which can be rotatably attached to the drawbar (52) or a longitudinal frame (11) of the motor vehicle by means of a foot pedal (54), wherein the control shaft (53) carries a locking hook (48), wherein the locking hook (48) is designed to engage correspondingly and releasably with a locking element (57) of the front section of the loading platform (8) projecting downwards in a vertical direction, and - a device (34) designed for the automatic, self-regulating, forced lowering of a raised, front or rear lift axle (21) of the motor vehicle or motor vehicle trailer (50) in relation to the direction of travel (39) upon separation of the connection between the locking hook (48) and the locking element (57) of the front section of the loading platform (8), and a device (51) for load-dependent lifting of a lift axle (21) that is forward or rearward in relation to the direction of travel (39) a) when the loading area (8) of the motor vehicle or motor vehicle trailer (50) is horizontally oriented and b) only if a specified maximum weight on the loading platform is not exceeded (8) and a hydraulic device (41) comprising the device (34) for automatically lowering a raised lift axle (21) and the device (51) for load-dependent raising of a lift axle (21) in direct or indirect connection with the hydraulic device (41) or wherein the device (34) for automatically lowering a raised lift axle (21) and the device (51) for load-dependent raising of a lift axle (21) are individually or jointly components of the hydraulic device (41).

Description

[0001] The present invention relates to a device for automatically lowering and load-dependent raising of a lift axle, with the features specified in claim 1.

[0002] Tandem axles with a lift axle, which can be raised independently of the load resting on the loading platform, are known from the prior art.

[0003] A significant disadvantage of these well-known tandem axles for motor vehicles or motor vehicle trailers with a lift axle that is not load-dependent but can always be raised is, in particular, that for legal reasons the lift axle may only be raised as a maneuvering aid during manual movement of the trailer when the trailer is unloaded.

[0004] These known tandem axles are also disadvantageous because the lift axle can be raised – accidentally or intentionally – even though the axle load remaining on the load axle then exceeds the maximum permissible axle load of the load axle. This creates the risk of axle breakage of the load axles and / or other component damage. From DE 35 25 027 A1, a device for a motor vehicle trailer with a tilting loading platform is known, comprising a device for automatically, autonomously, and positively controlled lowering of a raised lift axle of the motor vehicle trailer, located at the front of the vehicle in relation to the direction of travel, upon the presence of a tilting signal, and a device for load-dependent raising of the lift axle located at the front of the vehicle in relation to the direction of travel. a) with a horizontally oriented loading area of ​​the motor vehicle trailer and b) only if a predefinable maximum weight on the loading platform is not exceeded and a hydraulic device, wherein the device for automatically lowering the raised lift axle and the device for load-dependent raising of the lift axle are in direct or indirect connection with the hydraulic device.

[0005] The object of the present invention is therefore to provide a device in which the lift axle of a tandem axle may be raised for legal reasons – not only when the loading area is unloaded – but also when the loading area is partially loaded up to the permissible axle load of the load axle remaining on the ground, and – not only as a maneuvering aid during manual moving – but even during the operation of an attached trailer, and which reliably prevents the accidental or intentional raising of the lift axle of a tandem axle if – after raising the lift axle – the axle load remaining solely on the load axle would be greater than the maximum permissible axle load of the load axle.

[0005] According to the invention, this problem is solved by a device having the features specified in claim 1. Particularly preferred embodiments are the subject of the dependent claims.

[0006] Exemplary embodiments of the invention are described in more detail with reference to the drawings. The drawings show: Fig. 1 A side view of a motor vehicle trailer (50) with a horizontally oriented, non-tilted loading platform (8) and with a tandem axle comprising a lift axle (21) and a load axle (42), wherein the lift axle (21) is raised vertically upwards from the ground (38) by means of the device (4) according to the invention for automatic lowering and load-dependent raising, while the load axle (42) rests on the ground (38), wherein the operating element (59) of the changeover valve (35) is in the “raising” position (58) due to the horizontally oriented loading platform (8) and the hook-shaped closure, hereinafter referred to as the locking hook (48), of the locking device (47) still engaged, and the foot pedal (54) attached to the shaft (53) of the locking device (47) is oriented in a downward-moving position, pointing at least slightly upwards,wherein a control roller (18) rotatably mounted on the free end of the control lever (17) pivoted upwards by means of the lifting shaft (23) acts on the underside of a control surface (20) attached to the free end (7) of the pivot arm (2) of the lift axis (21) - when the lift axis (21) is raised vertically; Fig. 2 a side view of a motor vehicle trailer (50) with a horizontally oriented, non-tilted loading platform (8) and with a tandem axle comprising a lift axle (21) and a load axle (42), wherein the lift axle (21) and the load axle (42) rest on the base (38), wherein the control element (59) of the changeover valve (35) – due to the horizontally oriented loading platform (8) and the locking hook (48) of the locking device (47) still engaged – is in the “lift” position, and the foot pedal (54) attached to the lifting shaft (53) of the locking device (47) is oriented in a downward-actuated position, pointing at least slightly upwards, wherein a control roller (18) rotatably mounted on the free end of the control lever (17) pivoted downwards by means of the lifting shaft (23) is guided by the Fig. 2- is spaced apart by the lifting cylinder (13) and the return spring (14) - concealed control surface (20) - when the lift axle (21) is at rest on the base (38); Fig. 3 a hydraulic diagram for a device (4) according to the invention for supplying the lifting cylinder (13) with hydraulic fluid, wherein the loading platform (8) is tilted into a horizontal orientation and a switching valve (35) for switching between “raising” and “lowering” the lifting cylinder (13) is provided between the lifting cylinder (13) and the hydraulic fluid pump (37) and wherein the control element (59) of the switching valve (35) is aligned in the position corresponding to “raising” the lift axis (21); Fig. 4 a hydraulic diagram for a device (4) according to the invention for supplying the lifting cylinder (13) with hydraulic fluid, wherein the loading platform (8) is tilted in an inclined orientation and a switching valve (35) for switching between “raising” and “lowering” the lifting cylinder (13) is provided between the lifting cylinder (13) and the hydraulic fluid pump (37) and wherein the operating element (59) of the switching valve (35) is aligned in the position (60) - corresponding to “lowering” the lift axis (21); Fig. 5 a schematic, partial underview of the in Fig. 1 tandem axle shown with load axle (42) resting on the ground (38) and lift axle (21) raised upwards from the ground (38), from obliquely below and behind, wherein the control lever (17) of the lifting device (4) is oriented pointing upwards and the control roller (18) attached to the free end of the control lever (17) comes into contact with the control surface (20) provided at the free end (7) of the swivel arm (2) of the lift axle (21) - while raising the lift axle (21); Fig. 6 a schematic, partial top view of the in Fig. 2 tandem axle shown with load axle (42) and lift axle (21) resting on the ground (38), viewed obliquely from above and in front, wherein the control lever (17) points rearward in a horizontal orientation towards the rear of the vehicle (46), so that the control roller (18) attached to the free end of the control lever (17) is vertically spaced from the control surface (20) attached to the free end (7) of the pivot arm (2) of the lift axle (21); Fig. 7 a schematic, partial top view of the in the Fig. 2 and Fig. 6 tandem axle with load axle (42) and lift axle (21) resting on the ground (38), from above, wherein the control lever (17) points in a horizontal orientation towards the rear of the vehicle (46), so that the control roller (18) attached to the free end of the control lever (17) is vertically spaced from the control surface (20) attached to the free end (7) of the pivot arm (2) of the lift axle (21); Fig. 8 a schematic, partial side view of the in the Fig. 2, Fig. 6 and Fig. 7 tandem axle with load axle (42) and lift axle (21) resting on the base (38), wherein - for the sake of clarity - the lifting cylinder (13) acting between the mounting bracket (16) on the transverse frame (9) on the one hand and the linkage lever (15) of the lifting shaft (23) on the other hand and the associated return spring (14) running parallel to the lifting cylinder (13) are not shown, and wherein the control lever (17) points rearward in a horizontal orientation towards the rear of the vehicle (46), so that the control roller (18) attached to the free end of the control lever (17) is vertically spaced (67) from the control surface (20) attached to the free end (7) of the pivot arm (2) of the lift axle (21), wherein the angle α enclosed between the control lever (17) and the linkage lever (15) - when viewed from the side - is shown; Fig. 9 a schematic, partial side view of the in the Fig. 1 and Fig. Figure 5 shows a tandem axle with a load axle (42) resting on the base (38) and a lift axle (21) raised from the base (38), wherein – for the sake of clarity – the lifting cylinder (13) acting between the mounting tab (16) on the transverse frame (9) on the one hand and the linkage lever (15) of the lifting shaft (23) on the other hand, and the associated return spring (14) running parallel to the lifting cylinder (13) are not shown, wherein the control lever (17) is oriented in an almost vertical orientation, pointing upwards in the direction of the vertical, so that between the line (22), which runs between the geometric center (24) of the cross-sectional area of ​​the lifting shaft (23) and the projecting or recessed mounting point (27) of the control roller (18) on the control lever (17), on the one hand, and the line (19), which runs along the underside of the control surface (20), on the other hand,an angle γ is included and wherein the control roller (18) attached to the free end of the control lever (17) is in contact with the control surface (20) - for the purpose of raising the lift axis (21); Fig. 10 a schematic, partial view of the in the Fig. 1 and Fig. 2. Device (34) shown from the side for automatically lowering a raised lift axle (21), which is a component of the lifting device (4) according to the invention - and at the same time also represents a locking device - which is provided on the drawbar (52) of a trailer (50), for reversibly releasing a locking element (47) attached to the front (in the front area (55)) of the tilting loading platform (8), from obliquely below and behind, wherein the operating element (59) of the switching valve (35) - by means of a spring (31) acting between the longitudinal frame (11) and the operating element (59) - is held in the position (58) “raising the lift axle (21)”, the hook-shaped,pivotable closure (locking hook (48)) of the locking device (47) is held in engagement with the locking element (57) in the front area (55) of the horizontally oriented loading platform (8) and wherein the foot pedal (54) for the rotary drive of the shaft (53) of the locking device is provided in a pedalable orientation, pointing slightly upwards and raised; Fig. 11 A schematic, partial view of a device (34) for automatically lowering a raised lift axle (21), which is a component of the lifting device (4) according to the invention and also represents a locking device, which is attached to the drawbar (52) of a trailer (50) for reversibly releasing a locking element (47) attached to the front (in the front area (55)) of the tiltable loading platform (8), from an oblique angle below and behind, wherein the loading platform (8) is tilted into an oblique orientation, wherein the operating element (59) of the changeover valve (35) - by means of a spring (66) acting between the control attachment (56) on the shaft (53) for actuating the changeover valve (35) on the one hand and the operating element (59) of the changeover valve (35) on the other hand - is held in the position (60) “lowering of the lift axle (21)”, the hook-shaped, pivotable lock (locking hook (48)) of this device (34, 47,4) releases the locking element (57) in the front area (55) of the tilted loading platform (8), wherein the foot pedal (54) for the rotary drive of the shaft (53) of the locking device (47) is provided in a depressed orientation, pointing slightly downwards, and wherein the angle δ is shown which is enclosed between the control attachment (56) and the locking hook (48) - when viewed from the side along the control shaft (53); Fig. 12 a schematic, partial side view of a lifting device (4) according to the invention, which shows in particular the control lever (17) erected in the direction of the vertical - with the control roller (18) attached to its free end - and a line (19) running along the underside of the control surface (20), wherein an angle γ is enclosed between the line (19) and the line (22) - between the geometric center (24) of the cross-sectional area of ​​the lifting shaft (23) on the one hand and the projecting or recess-shaped mounting location (27) of the control roller (18) on the control lever (17) on the other hand - wherein between the dead center line (68) - which represents an imaginary line extending from the contact point (69) between the outer circumference of the control roller (18) on the one hand and the underside of the control surface (20) on the other hand, when the control lever (17) is pivoted upwards in the direction of the vertical,originates and the line (22) includes a reserve angle η - to prevent a "snap" [= rolling of the control roller (18) along the underside of the control surface (20) beyond the dead center] of the control lever (17) - wherein the control surface (20) can be attached to the free end (7) of the associated pivot arm (2) by means of a bracket (29), wherein the control surface (20) - in a side view - has a straight form and wherein the imaginary line (19) running along the underside of the control surface (20) is aligned approximately parallel to and spaced apart from the longitudinal axis of the pivot arm (2).

[0007] As already mentioned in the Fig. 1 to Fig. As can be seen from paragraph 12, the present invention relates in particular to a device (4) for automatically lowering and load-dependent raising of a lift axle (21).

[0008] Typically, this device (4) may initially comprise one or more devices (34) for automatically lowering a raised lift axle (21).

[0009] Within the scope of the present invention, the phrase “automatic lowering” of a raised lift axle means that the device (34) – for automatically lowering a raised lift axle (21) – can, for example, with respect to the direction of travel (39), automatically, autonomously and with positive coupling lower the front or rear lift axle (21) at least when a) the loading platform (8) of a motor vehicle or a motor vehicle trailer (50) is tilted and inclined and / or b) the weight on the loading platform (8) is greater than a predefinable maximum permissible limit, e.g., for the axle load of the load axle (42).

[0010] In general, the device (4) - in particular for load-dependent lifting of the lift axle (21) - comprises, in addition to the device (34), one or more devices (51) for load-dependent lifting of a lift axle (21) that is forward or rearward with respect to the direction of travel (39).

[0011] For the purposes of the present invention, the term "load-dependent lifting" means that lifting the lift axle (21) is only possible if a) the loading platform (8) of a motor vehicle or motor vehicle trailer is horizontally oriented and b) the weight bearing down on the loading platform (8) is less than a predefinable maximum weight. The "predefinable maximum weight" is, for example, the weight that is permissible as the maximum axle load for the load axle (42).

[0012] In general, the device (4) according to the invention comprises, in addition to the devices (34) and (51), a hydraulic device (41).

[0013] In general, the devices (34) and (51) are directly or indirectly connected to the hydraulic device (41). Alternatively, the devices (34) and (51) can be components of the hydraulic device (41), either individually or together.

[0014] As a rule, the one or more devices (34) for automatically lowering a raised lift axle (21) when the loading platform (8) of a motor vehicle or motor vehicle trailer (50) is tilted and inclined can each be designed in such a way that they include at least one locking device (47).

[0015] This locking device (47) can serve to releasably lock the front section of the tilting loading platform (8) to the frame of a motor vehicle or to the drawbar (52) of a motor vehicle trailer (50). The locking device (47) can, for example, comprise a control shaft (53) oriented perpendicular to the longitudinal axis of the drawbar (52) or the motor vehicle.

[0016] In preferred embodiments of the device (4) according to the invention, this control shaft (53) can be rotatably attached to the drawbar (52) or the longitudinal frame (11) of a motor vehicle by means of a foot pedal (54).

[0017] The control shaft (53) typically carries a locking hook (48) and a control attachment (56).

[0018] Preferably, the control attachment (56) and the locking hook (48) – when viewed from the side along the control shaft (53) – can enclose an angle δ which lies in the range of 5.0° to 40.0°, preferably in the range of 9.0° to 35.0°, and in particular in the range of 12.0° to 30.0° (see Fig. 11).

[0019] The Fig. Figure 10 shows that the hook-shaped, pivotable locking hook (48) of the locking device (47) and the foot pedal (54) which is positively attached to the control shaft (53) - when viewed from the side along the control shaft (53) - can enclose an angle ε which lies in the range of 30.0° to 80.0°, preferably in the range of 35.0° to 75.0°, in particular in the range of 39.0° to 71.0°.

[0020] Preferably, the locking hook (48) can be designed to engage correspondingly and releasably with a locking element (57) of the front section (in the front area (55)) of the loading platform (8) projecting downwards in a vertical direction.

[0021] In particularly preferred embodiments of the device (4) according to the invention, the control attachment (56) provided on the control shaft (53) is in a positively guided connection with an operating element (59) of a hydraulic switching valve (35) of the hydraulic device (41).

[0022] As a rule, this control element (59) allows the switching valve (35) of the hydraulic device (41) to be switched between a hydraulic fluid flow (61) between a position (58) to raise the lift axle (21) and a position (60) to lower the lift axle (21).

[0023] This coupling between control shaft (53) and operating element (59) of the hydraulic switching valve (35) of the hydraulic device (41) results in the automatic, self-regulating and forced lowering of a raised lift axle (21) when the connection between the drawbar-side locking hook (48) and the locking element (57) of the front section (in the front area (55)) of the loading platform (8) is separated by actuation of the foot pedal (54).

[0024] Within the scope of the present invention, the one or more devices (51) for load-dependent lifting of a lift axle (21) with a horizontally oriented loading platform (8) of a motor vehicle or a motor vehicle trailer (50) can each comprise one or more hydraulic devices (41) in which one or more electrically or manually operable hydraulic pumps (37) are provided (see in particular Fig. 3 and Fig. 4).

[0025] In general, the one or more hydraulic pumps (37) contained in the hydraulic device (41) can be directly or indirectly connected to one or more lifting cylinders (13) - for the indirect or direct lifting of the lift axle (21) - for example via one or more hydraulic lines (61).

[0026] Especially the Fig. 3 and Fig. Figure 4 shows that one or more pressure relief valves (63) can be provided downstream of each lifting cylinder (13). Preferably, these pressure relief valves (63) can be connected downstream, either directly or indirectly, to a hydraulic fluid tank (64).

[0027] In particular, the pressure relief valve(s) (63) can be adjusted by means of one or more adjustment devices (65) to the maximum permissible pressure allowed on the loading platform (8) for raising the lift axle (21).

[0028] As a rule, this maximum permissible pressure can correspond, for example, to the maximum permissible axle load of the load axle remaining on the ground (42).

[0029] In this case, it is not possible to raise the lift axle (21) directly or indirectly by means of one or more lifting cylinders (13) - due to the opening of the pressure relief valve(s) (63) - if the weight on the loading platform (8) is greater than the limit value of the maximum permissible axle load of the load axle (42) remaining on the ground specified by the adjusting device (65) of the pressure relief valve (63).

[0030] In particularly preferred embodiments of the device (4) according to the invention, the adjusting device (65) of the pressure relief valve (63) can be designed to be sealable and thus prevent improper tampering.

[0031] The provision of this pressure relief valve (63) also has the advantage that if the loading platform (8) is loaded – for example, by means of a crane – with a weight that is greater than the limit value specified by the adjusting device (65) [e.g., maximum permissible axle load of the load axle (42)] of the pressure relief valve (63), the pressure relief valve (63) opens automatically, autonomously and by force control, so that an automatic emptying of the lifting cylinder (13) – and thus an automatic lowering of the lift axle (21) – then takes place.

[0032] From the Fig. 3 and Fig. 4 further indicates that the lifting cylinder (13) of the hydraulic device (41) is in indirect or direct connection via one or more hydraulic lines (61) with one or more electrically and / or manually operated hydraulic pumps (37), wherein a switching valve (35) may be provided upstream of the lifting cylinder (13).

[0033] With the aid of this changeover valve (35), a continuous connection between the lifting cylinder (13) and the hydraulic pump (37) can be established in the "lifting" position (58). Conversely, in the "lowering" position (60), the changeover valve (35) can interrupt the connection between the lifting cylinder (13) and the hydraulic pump (37) and instead establish a connection between the lifting cylinder (13) and the hydraulic fluid tank (64). In preferred embodiments of the device (4) according to the invention, one or more throttle check valves (44) can be provided between the lifting cylinder (13) and the changeover valve (35) to adjust the return velocity of the hydraulic fluid into the hydraulic fluid tank (64) (see Fig. 3 and Fig. 4).

[0034] Preferably a pressure relief valve (63) can be provided between the lifting cylinder (13) and the hydraulic fluid tank (64), which opens automatically, autonomously and by positive force when the loading platform (8) is loaded with a weight that is greater than the permissible axle load of the load axle (42).

[0035] In addition, one or more manual valves (62) may be provided upstream of the switching valve (35) for manually lowering the raised lift axle (21) when the loading platform (8) is horizontal.

[0036] In particularly preferred embodiments of the device (4) according to the invention, in the case of the device (51) for load-dependent lifting of a lift axis (21), both the load axis (42) and the lift axis (21) can each have a rotation axis (1) located between their two pivot arms (2) for their two pivot arms (2).

[0037] One or more rotatable wheels (3) can be attached directly or indirectly to each of the two free ends (7) of each swivel arm (2).

[0038] As a rule, the device (51) for load-dependent lifting of a lift axle (21) can be perpendicular to the vehicle's longitudinal axis (40; see Fig. 5) comprise a lifting shaft (23) aligned and rotatably mounted about its geometric cross-sectional center (24).

[0039] Preferably, a linkage lever (15) for engaging a lifting cylinder (13) which exerts pressure, for example, between the transverse frame (9) and the linkage lever (15), can be provided in a fixed position on the outer circumference of the lifting shaft (23).

[0040] As a rule, the lifting cylinder (13) can act on the one hand on a protruding or recessed mounting point (28) on the linkage lever (15) of the lifting shaft (23) and on the other hand indirectly or directly on the transverse frame (9) or the longitudinal frame (11).

[0041] The distance between the geometric center (24) of the lifting shaft (23) and the mounting location (28) of the lifting cylinder (13) on the linkage lever (15) can, for example, be in the range of 4.0 cm to 15.0 cm, preferably in the range of 5.0 cm to 13.0 cm, and in particular in the range of 7.0 cm to 11.0 cm.

[0042] In particularly preferred embodiments of the device (4) according to the invention, a control lever (17) can be provided in a fixed position on the outer circumference of the lifting shaft (23), on which the linkage lever (15) is also attached.

[0043] This control lever (17) can carry one or more rotatable control rollers (18) in the area of ​​its free end - at the projecting or recessed mounting point (27) for the control roller (18) (see in particular Fig. 5, Fig. 7 and Fig. 12).

[0044] Especially from Fig. Figure 8 shows that - when viewed from the side - the control lever (17) and the linkage lever (15) are arranged in the shape of a letter V one behind the other and offset from each other in a V-shape on the lifting shaft (23) and the vertically upward pointing opening angle α of this V-shaped offset - when viewed from the side - can be, for example, in the range of 45° to 85°, preferably in the range of 48° to 82°, and in particular in the range of 50° to 75°.

[0045] Already Fig. It can be seen from Figure 12 that in the area of ​​the inside of the lifting swivel arm (2) of the lift axis (21) and in the area of ​​its free end (7), a sliding rail-shaped or roller track-shaped control surface (20) - in an almost parallel orientation to the longitudinal axis of the swivel arm (2) of the lift axis (21) - can be provided indirectly via a support (29) or directly.

[0046] As a rule, the control roller (18) rotatably mounted at the free end of the control lever (17) in the mounting location (27) can roll at least partially on the underside of the control surface (20) when the linkage lever (15) of the lifting shaft (23) is extended to its full length by means of the lifting cylinder (13) acting between the linkage lever (15) and, for example, the transverse frame (9).

[0047] During this rolling movement of the control roller (18) along the underside of the control surface (20), the control lever (17) with the control roller (18) attached to it in the mounting location (27) is pushed upwards and thereby the lift axis (21) is raised vertically upwards.

[0048] As can be seen particularly from the Fig. 5, Fig. 6 and Fig. As can be seen in Figure 7, a return spring (14) running parallel to the lifting cylinder (13) can – for the purpose of retracting the lifting cylinder (13) and lowering the lift axis (21) vertically onto the ground (38) – pull the linkage lever (15) back from a deflected position – due to the maximum extension of the hydraulic cylinder (13) – to an oppositely inclined position.

[0049] In particular Fig. Figure 8 shows that when the wheel (3) of the lift axle (21) rests on the surface (38), the control roller (18) can be spaced a distance (67) from the underside of the control surface (20), which is, for example, in the range of 40.0 mm to 110.0 mm, preferably in the range of 50.0 mm to 100.0 mm, and in particular in the range of 70.0 mm to 90.0 mm.

[0050] In preferred embodiments of the device (4) according to the invention, the geometric relationships between a) the projecting or recessed mounting location (28) of the lifting cylinder (13) on the linkage lever (15) of the lifting shaft (23) on the one hand, and b) the projecting or recessed mounting location (27) of the control roller (18) on the control lever (17) of the lifting shaft (23) on the other hand, and c) the axis of rotation (1) of the respective lifting swivel arm (2), can follow the following formula: l−r−v⋅sin βo−h⋅cos βp=0; • where: l = length of the lifting cylinder (13); r = radius of the control roller (18) at the control roller mounting point (27) on the free end of the control lever (17); • v = horizontal distance between the geometric cross-sectional center (= mounting location 27) of the control roller (18) on the one hand and the respective axis of rotation (1) on the frame projection (10) for the lifting swivel arm (2) on the other hand; • βo = included angle between a line which runs parallel to the rail-shaped control surface (20) of the guide (29) for the control roller (18), on the one hand, and a vertical line imaginary through the geometric center (= mounting point 27) of the control roller (18), on the other hand; h = vertical distance between the geometric cross-sectional center (= mounting point 27) of the control roller (18) on the one hand, and an imaginary horizontal line on the other hand, which runs horizontally through the axis of rotation (1) of the lift swivel arm (2).

[0051] Especially the Fig. 9 and Fig. Figure 12 shows that - in a side view - between a line (19) running along the underside of the control surface (20) and pointing in the direction of the axis of rotation (1) belonging to the respective pivot arm (2) on the one hand and a line (22) between the geometric center (24) of the cross-sectional area of ​​the lifting shaft (23) on the other hand, an angle γ is included, which can be, for example, in the range of 140.0° to 90.0°, preferably in the range of 130.0° to 90.0°, and in particular in the range of 120.0° to 90.0°.

[0052] How Fig. As can be seen from Figure 12, with the lifting cylinder (13) fully extended and the control lever (17) pivoted to the maximum in the direction of the vertical, a dead center line (68) can be perpendicular to the line (19) running through the contact point (69) between the outer circumference of the control roller (18) of the control lever (17) on the one hand and the underside of the control surface (20) on the other.

[0053] Also the Fig. It can be seen from Figure 12 that at this contact point (69) the line (22) between the geometric center (24) of the cross-sectional area of ​​the lifting shaft (23) and the projecting or recessed mounting location (27) of the control roller (18) on the control lever (17) on the one hand, and the dead center line (68) on the other hand, can enclose an angle η which may be in the range of 0.5° to 50.0°, preferably in the range of 0.7° to 40.0°, and in particular in the range of 0.9° to 30.0°.

[0054] Maintaining this angle η can serve as a “reserve” to the dead center line (68) and as a measure to prevent the control lever (17) from “snapping”.

[0055] The term “overshooting” in the context of the present invention shall in particular be understood to mean a swinging of the control lever (17) beyond the dead center line (68) in the direction of the pivoting movement of the control lever (17) or an overrotation of the control lever (17) beyond the dead center line (68) in a direction opposite to the axis of rotation (1) of the associated pivot arm (2).

[0056] The Fig. Figure 12 further shows that the line (19) running along the underside of the control surface (20) when viewed from the side can be, for example, essentially tangential to the pivot radius swept by the control roller (18) during the pivoting process of the control lever (17).

[0057] In particularly preferred embodiments of the device (4) according to the invention, the distance between the control surface (20) and the line (19) on the one hand and the geometric center (24) of the cross-sectional area of ​​the lifting shaft (23) on the other hand can be at least somewhat shorter than this swept pivot radius, so that the angle γ (see Fig. 9 and Fig. 12) is always at least slightly larger than 90°.

[0058] In particularly preferred embodiments of the device (4) according to the invention, the lifting cylinder (13) can be extended by pressurizing the hydraulic fluid and can be retracted from an extended, long state to a retracted, short state by a return spring (14).

[0059] In summary, it can be stated that within the scope of the present invention a device (4) is provided for automatically lowering and load-dependent raising a lift axle (21) of the tandem axle of a motor vehicle or a motor vehicle trailer.

[0060] A particular advantage of the device (4) according to the invention is that, in the case of its use, even during driving operation, a significantly reduced tire wear occurs on the lift axle (21), which can then be raised.

[0061] A particularly significant advantage of the device (4) according to the invention is further evidenced by the fact that, with its help, an accidental or intentional lifting of the lift axle (21) of a tandem axle is reliably prevented if - after lifting the lift axle (21) - the axle load remaining solely on the load axle (42) is greater than the maximum permissible axle load of the load axle (42).

[0062] This means that the load-dependent lifting of the lift axle (21) in the device (4) according to the invention is only possible if the load-related pressure in the hydraulic line (61) does not exceed the limit value for the maximum permissible axle load on the load axle (42) that can be set at the pressure limiting valve (63) by means of the adjusting device (65).

[0063] An impermissible lifting of the lift axle (21) - which would otherwise be at risk of overloading the load axle (42) which remains on the ground (38) - can therefore be safely avoided with the device (4) according to the invention.

[0064] Another significant advantage of the device (4) according to the invention is that, in the event of an exceedance of the maximum permissible axle load on the load axle (42) - with the lift axle (21) raised - the lift axle (21) is automatically lowered.

[0065] This advantage is made possible in particular by the use of the pressure relief valve (63) adjustable by means of the adjustment device (65) in the hydraulic fluid circuit for the lifting cylinder (13).

[0066] Furthermore, in the case of the device according to the invention, an automatic lowering of the lift axle (21) occurs, which is forcibly coupled with the unlocking of the loading platform (8), when the loading platform (8) - starting from a horizontal, tilted position - is to be pivoted into an inclined, tilted position: For this purpose, the front section (55) of the loading platform (8) must be disconnected from the drawbar (52) of a trailer (50) or from the frame (9, 11) of a motor vehicle by means of a locking device (47). During the unlocking pivoting movement of the locking hook (48), this locking device (47) automatically and forcibly couples with the unlocking action, switching and aligning the control element (59) of the changeover valve (35) to the "lowering" position (60) for lowering the lift axle (21).

[0067] Further advantages of the device (4) according to the invention consist of its clear design, resulting in operational reliability and low susceptibility to malfunctions. In particular, the device (4) according to the invention does not require the use of electronics and complex mechanics, which are generally prone to malfunctions. The structurally simple components used to manufacture the device (4) according to the invention result in exceptionally low manufacturing and operating costs.

[0068] In the Fig. 1 to Fig.In Figure 12 of the present invention, the front axle of a tandem axle in the direction of travel (39) has always been depicted as the "lift axle" (21). Of course, within the scope of the present invention, it is possible to design the rear axle of a tandem axle with respect to the direction of travel (39) as the "lift axle" (21) and the front axle of a tandem axle as the "load axle" (42). Due to the design of the front axle (39) of a tandem axle as a "lift axle" (21), a greater distance to the rear axle of the towing vehicle can be achieved by creating a larger wheelbase. This leads to improved driving stability of the trailer during operation.

[0069] Lifting the rear axle of a tandem axle, which is located at the rear in the direction of travel (39), leads to advantages in manual shunting operations due to the resulting smaller wheelbase. Reference symbol list 1 pivot axis on the frame projection 10 for a swivel arm 2 2 swivel arms 3-wheeler 4 Device for automatically lowering and load-dependent raising a lift axle 21; comprising 34 + 51 + 41 5 leaf spring 6 swivel axes for loading platform 7 free end of the respective swivel arm 2 8 tilting loading platforms 9 cross frames 10 Frame projection on the cross frame 9 for receiving the pivot axes 1 11 longitudinal frames 12 bearings for lifting shaft 23; projecting, attached to the longitudinal frame 11 13 lifting cylinders 14 Return spring 15 Linkage lever of the lifting shaft 23, for engagement of the lifting cylinder 13 and the return spring 14 16 Mounting tab on the cross frame 9 for lifting cylinder 13 and return spring 14 17 control levers 18 Control roller, rotatable, attached to control lever 17 19 imaginary line running along the underside of the control surface 20 and its extension on both sides 20 Control surface at the free end 7 of the swivel arm 2 of the lift axis 21; slide rail-shaped or roller track-shaped for rolling the control roller 18 21 Lift axle 22 Line between the geometric center 24 of the cross-sectional area of ​​the lifting shaft 23 on the one hand and the projecting or recessed mounting point 27 of the control roller 18 on the control lever 17 on the other hand; 23 Lifting shaft 24 geometric center of the cross-sectional area of ​​the lifting shaft 23 25 imaginary line between geometric cross-sectional center 24 of the lifting shaft 23 and the mounting point 27 of the control roller 18 at the free end of the control lever 17 26 imaginary line through the geometric center 24 of the lifting shaft 23 on the one hand and the free end of the linkage lever 15 for the action 29 of the lifting cylinder 13 on the other hand 27 Projecting or recessed mounting location of the control roller 18 on the control lever 17 28 Projecting or recessed mounting location of the lifting cylinder 13 on the linkage lever 15 of the lifting shaft 23 29 Mounting bracket for control surface 20, at the free end of the lifting swivel arm 2 30 Length of the lifting cylinder 13 31 Spring between longitudinal frame 11 and operating element 59 of the changeover valve 35; part of the locking device 47 32 horizontal distance v between the geometric cross-sectional center (=mounting point 27) of the control roller 18 and the axis of rotation 1 on the frame projection 10 for the lifting swivel arm 2 33 vertical distance h between the geometric cross-sectional center (=attachment point 27) of the control roller 18 on the one hand and an imaginary horizontal line on the other hand, which runs horizontally through the axis of rotation 1 of the lifting swivel arm 2 34 Device for automatically lowering a raised lift axle 21 35 Diverter valve 36 Lever for operating the changeover valve 35 37 Hydraulic pump 38 Subsurface 39 Direction of travel 40 Longitudinal axis of the vehicle or trailer 41 Hydraulic equipment 42 load axle 43 Control lever for hydraulic pump 37 44 Throttle check valve between changeover valve 35 and lifting cylinder 13 45 Front of a trailer 50 46 Rear of a trailer 50 47 Locking device for tilting loading platform 8 - in the front area of ​​the drawbar 52 or in the front area of ​​the longitudinal frame 11 - for reversibly releasing a locking element 57 attached to the front of the tilting loading platform 8; coupled with the operating element 59 of the changeover valve 35 48 Locking hooks of the locking device 47 49 Pressure relief valve to protect the hydraulic pump 37 from overpressure, connected in parallel to the hydraulic pump 37 50 followers 51 Device for load-dependent lifting of a lift axle 21 52 Drawbar of a trailer 50 53 Shaft of the locking device 47, perpendicular to the longitudinal axis of the trailer 50 or the motor vehicle 54 Foot pedal, positively engaged on the shaft 53 55 Front area of ​​the loading platform 8 56 Control attachment on shaft 53 for actuating the changeover valve 35 57 Locking element in the front area 55 of the loading area 8 58 Position of the control element 59 of the changeover valve 35: Raising the lift axle 21 59 Control element of the changeover valve 35 60 Position of the control element 59 of the changeover valve 35: Lowering of the lift axis 21 61 Hydraulic line 62 Manual valve, upstream of the hydraulic pump 37 63 Pressure relief valve, adjustable to the maximum permissible axle load of the load axle 42; opens into the tank 64 when this pressure is reached. 64 Hydraulic fluid tank 65 Adjustment device of the pressure relief valve 63; for setting a limit pressure which corresponds to the maximum permissible axle load of the load axle 42 66 Spring between operating element 59 of the changeover valve 35 and the control attachment 56 on the shaft 53 of the locking device 47 67 Distance between the top of the control roller 18 and the bottom of the control surface 20 while the wheel 3 is in contact with the ground 38 68 Dead center line, imaginary line that originates from the contact point 69 between the outer circumference of the control roller 18 on the one hand and the underside of the control surface 20 on the other hand - with the control lever 17 pivoted upwards in the direction of the vertical - and is at an angle of 90° to the line 19 69 Contact point between the outer circumference of the control roller 18 on the one hand and the underside of the control surface 20 on the other hand, with the control lever 17 pivoted upwards in the direction of the vertical α Angle - in side view - enclosed between a line 25 conceived through the geometric center 24 of the lifting shaft 23 and the mounting point of the control roller 18 on the free end of the control lever 17 on the one hand and a line 26 conceived through the geometric center 24 of the lifting shaft 23 and the free end of the linkage lever 15 for the action of the lifting cylinder 13 on the other hand; γ angle - in side view - enclosed between an imaginary line 19, which runs on both sides along the underside of the control surface 20, on the one hand, and a line 22, which runs through the geometric center 24 of the cross-sectional area of ​​the lifting shaft 23 and the projecting or recess-shaped mounting point 27 of the control roller 18 on the control lever 17, on the other hand - with the control lever 17 pivoted in the direction of the vertical for the purpose of raising the lift axis 21; δ Angle enclosed between the control attachment 56 and the locking hook 48 - when viewed from the side along the control shaft 53; ε angle enclosed between the hook-shaped, pivotable locking hook 48 of the locking device 47 and the foot pedal 54 which is positively attached to the control shaft 53 - when viewed from the side along the control shaft 53; η Reserve angle, between line 22 and dead center line 68 - to prevent the control lever from “snapping” (17).

Claims

[1] Device (4) for a motor vehicle or a motor vehicle trailer (50) having a tiltable loading platform (8), comprising - a locking device (47) for releasably locking the front section of the loading platform (8) to a frame (9, 11) of a motor vehicle or to a drawbar (52) of a motor vehicle trailer (50), wherein the locking device (47) comprises a control shaft (53) oriented perpendicular to the longitudinal axis of the drawbar (52) or of the motor vehicle, which can be rotatably attached to the drawbar (52) or a longitudinal frame (11) of the motor vehicle by means of a foot pedal (54), wherein the control shaft (53) carries a locking hook (48), wherein the locking hook (48) is designed to engage correspondingly and releasably with a locking element (57) of the front section of the loading platform (8) projecting downwards in a vertical direction, and - a device (34) designed for the automatic, self-regulating, forced lowering of a raised, front or rear lift axle (21) of the motor vehicle or motor vehicle trailer (50) in relation to the direction of travel (39) upon separation of the connection between the locking hook (48) and the locking element (57) of the front section of the loading platform (8), and a device (51) for load-dependent lifting of a lift axle (21) that is forward or rearward in relation to the direction of travel (39) a) when the loading area (8) of the motor vehicle or motor vehicle trailer (50) is horizontally oriented and b) only if a specified maximum weight on the loading platform is not exceeded (8) and a hydraulic device (41) comprising the device (34) for automatically lowering a raised lift axle (21) and the device (51) for load-dependent raising of a lift axle (21) in direct or indirect connection with the hydraulic device (41) or wherein the device (34) for automatically lowering a raised lift axle (21) and the device (51) for load-dependent raising of a lift axle (21) are individually or jointly components of the hydraulic device (41). [2] Device (4) according to claim 1, wherein the control shaft (53) further carries a control attachment (56), wherein the control attachment (56) and the locking hook (48) – when viewed from the side along the control shaft (53) – enclose an angle δ which lies in the range of 5.0° to 40.0°, wherein the locking hook (48) of the locking device (47) and the foot pedal (54) which is positively connected to the control shaft (53) – when viewed from the side along the control shaft (53) – enclose an angle ε which lies in the range of 30.0° to 80.0°, and wherein the control attachment (56) provided on the control shaft (53) is in a positively guided connection with an operating element (59) of a changeover valve (35) of the hydraulic device (41),wherein this control element (59) enables switching of the changeover valve (35) of the hydraulic device (41) for a hydraulic fluid flow (61) between a position (58) for raising the lift axle (21) and a position (60) for lowering the lift axle (21). [3] Device (4) according to one of claims 1 or 2 , characterized by, that the device (51) for load-dependent lifting of a lift axle (21) with the loading platform (8) of the motor vehicle or motor vehicle trailer (50) in a horizontally oriented position is connected to one or more hydraulic devices (41), wherein these comprise one or more electrically or manually operated hydraulic pumps (37), which are directly or indirectly connected to one or more lifting cylinders (13) – for the direct or indirect lifting of the lift axle (21) – via a hydraulic line (61), wherein one or more pressure relief valves (63) are provided downstream of each lifting cylinder (13), which are directly or indirectly connected downstream to a hydraulic fluid tank (64), wherein the pressure relief valve(s) (63) are adjustable to the maximum permissible pressure for lifting the lift axle (21) by means of one or more adjustment devices (65),wherein this maximum permissible pressure corresponds to the maximum permissible axle load of the load axle (42) remaining on the ground, so that an indirect or direct lifting of the lift axle (21) by means of one or more lifting cylinders (13) - due to an opening of the pressure relief valve(s) (63) - is not possible if the weight on the loading platform (8) is greater than the limit value of the maximum permissible axle load of the load axle (42) remaining on the ground, which can be set via the adjusting device (65) of the pressure relief valve (63). [4] Device (4) according to one of claims 1, 2 or 3, characterized by, that one or more lifting cylinders (13) of the hydraulic device (41) are in direct or indirect communication via one or more hydraulic lines (61) with one or more electrically and / or manually operated hydraulic pumps (37), wherein a changeover valve (35) is provided upstream of the lifting cylinder(s) (13), with the aid of which - in the “lifting” position (58) - a continuous connection between the lifting cylinder(s) (13) and the hydraulic pump (37) can be established and which - in the “lowering” position (60) - interrupts the connection between the lifting cylinder(s) (13) and the hydraulic pump (37) and instead establishes a connection between the lifting cylinder(s) (13) and the hydraulic fluid tank (64),wherein one or more throttle check valves (44) are provided between the lifting cylinder(s) (13) and the changeover valve (35) - for adjusting the return velocity of the hydraulic fluid into the hydraulic fluid tank (64) -, wherein a pressure relief valve (63) is provided between the lifting cylinder(s) (13) and the hydraulic fluid tank (64), which opens automatically, autonomously and by force control when the loading platform (8) is loaded with a weight greater than the permissible axle load of the load axle (42), and wherein one or more manual valves (62) are provided upstream of the changeover valve (35) for manually lowering the raised lift axle (21) when the loading platform (8) is horizontal. [5] Device (4) according to one of claims 1, 2, 3 or 4, characterized by, that in the case of the device (51) for load-dependent lifting of a lift axle (21), both the load axle (42) and the lift axle (21) each have a pivot axis (1) located between pivot arms (2) thereof for their two pivot arms (2), wherein one or more rotatable wheels (3) are attached directly or indirectly to each of the two free ends (7) of each pivot arm (2), wherein the device (51) for load-dependent lifting of a lift axle (21) comprises a lifting shaft (23) oriented perpendicular to the vehicle longitudinal axis (40) and rotatably mounted about its geometric cross-sectional center (24), wherein a linkage lever (15) for engaging a lifting cylinder (13) exerting pressure between a transverse frame (9) and one or more linkage levers (15) is provided in a fixed position on the outer circumference of the lifting shaft (23),wherein the lifting cylinder(s) (13) acts on one side on a projecting or recessed mounting point (28) on the linkage lever (15) of the lifting shaft (23) and on the other side indirectly or directly on the transverse frame (9) or the longitudinal frame (11), the distance between the geometric center (24) of the lifting shaft (23) and the mounting point (28) of the lifting cylinder(s) (13) on the linkage lever (15) is in the range of 4.0 cm to 15.0 cm and wherein, A control lever (17) is fixedly provided on the outer circumference of the lifting shaft (23), on which the linkage lever (15) is also mounted. In the area of ​​its free end, the control lever (17) carries one or more rotatable control rollers (18) at the projecting or recessed mounting point (27) for the control roller (18). Viewed from the side, the control lever (17) and the linkage lever (15) are arranged in the shape of a letter V, one behind the other and offset from each other in a V-shape, on the lifting shaft (23). The vertically upward opening angle α of this V-shaped offset, viewed from the side, lies in the range of 45° to 85°. In the area of ​​the inside of the lifting swivel arm (2) of the lift axis (21) and in the area of ​​its free end (7),A sliding rail-shaped or roller track-shaped control surface (20) is provided in an almost parallel orientation to the longitudinal axis of the pivot arm (2) of the lift axis (21) - indirectly via a bracket (29) or directly - wherein the control roller (18) rotatably mounted at the free end of the control lever (17) in the mounting location (27) rolls at least section by section on the underside of the control surface (20) when the linkage lever (15) of the lifting shaft (23) is extended to its full length by means of the lifting cylinder(s) (13) acting between the linkage lever (15) and the transverse frame (9),The control lever (17) with the control roller (18) attached to it at the mounting point (27) is pushed upwards, thereby raising the lift axle (21) vertically upwards, and a return spring (14) running parallel to the lifting cylinder(s) (13) – for the purpose of retracting the lifting cylinder(s) (13) and lowering the lift axle (21) vertically onto the ground (38) – pulls the linkage lever (15) back from a deflected position – due to the maximum extension of the lifting cylinder(s) (13) – to an oppositely inclined position, and when the wheel (3) is in contact with the ground (38), the control roller (18) is spaced from the underside of the control surface (20) at a distance (67) which lies in the range of 40.0 mm to 110.0 mm. [6] Device (4) according to claim 5, characterized by, that the geometric relationships between a) the projecting or recessed mounting location (28) of one or more lifting cylinder(s) (13) on the linkage lever (15) of the lifting shaft (23) on the one hand and b) the projecting or recessed mounting location (27) of the control roller (18) on the control lever (17) of the lifting shaft (23) on the other hand and c) the axis of rotation (1) of the respective lifting swivel arm (2) follow the following formula: l−r−v⋅sin βo−h⋅cos βp=0; where: l = length of the lifting cylinder(s) (13); r = radius of the control roller (18) at the control roller mounting point (27) on the free end of the control lever (17); v = horizontal distance between the geometric cross-sectional center (= mounting location 27) of the control roller (18) on the one hand and the respective axis of rotation (1) on a frame projection (10) for the lifting swivel arm (2) on the other hand; β o= included angle between a line which runs parallel to the sliding control surface (20) of the guide (29) for the control roller (18), on the one hand, and a vertical line imagined through the geometric center (=mounting point 27) of the control roller (18), on the other hand; h = vertical distance between the geometric cross-sectional center (= mounting location 27) of the control roller (18) on the one hand and an imaginary horizontal line on the other hand, which passes through the axis of rotation (1) of the lift swivel arm. [7] Device (4) according to claim 5 or 6, characterized by, that - in a side view - between a line (19) running along the underside of the control surface (20) and pointing in the direction of the axis of rotation (1) belonging to the respective pivot arm (2) on the one hand and a line (22) between the geometric center (24) of the cross-sectional area of ​​the lifting shaft (23) on the other hand, an angle γ is enclosed which lies in the range of 140.0° to 90.

0. [8] Device (4) according to any one of claims 5 to 7, characterized by, that - with the lifting cylinder (13) fully extended and thus the control lever (17) pivoted maximally in the direction of the vertical - at the contact point (69) reached between the outer circumference of the control roller (18) of the control lever (17) on the one hand and the underside of the control surface (20) on the other hand, a dead center line (68) is perpendicular to the line (19) running through the contact point (69) and along the underside of the control surface (20), wherein at this contact point (69) the line (22) between the geometric center (24) of the cross-sectional area of ​​the lifting shaft (23) and the projecting or recessed mounting location (27) of the control roller (18) on the control lever (17) on the one hand, and the dead center line (68) on the other hand, enclose an angle η which lies in the range of 0.5° to 50.0°,where maintaining this angle η serves as a "reserve" to the dead center line (68) and as a measure to prevent the control lever (17) from "snapping" in the sense of swinging beyond the dead center line (68) in the direction of the pivoting movement of the control lever (17) or over-rotating beyond the dead center line (68) in the direction opposite to the direction of the axis of rotation (1) of the associated pivot arm (2). [9] Device (4) according to any one of claims 5 to 8, characterized by, that the line (19) running along the underside of the control surface (20) when viewed from the side is tangential to the pivot radius swept by the control roller (18) during the pivoting process of the control lever (17), wherein the distance between the control surface (20) and the line (19) on the one hand and the geometric center (24) of the cross-sectional area of ​​the lifting shaft (23) on the other hand is at least slightly shorter than this swept pivot radius, so that the angle γ is always at least slightly greater than 90°. [10] Device (4) according to any one of claims 1 to 9, characterized by , that one or more lifting cylinders (13) can be extended by pressurizing the hydraulic fluid and can be retracted from an extended, long state to a retracted, short state by a return spring (14).

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