FI129208B - Offset Adaptor, a Propulsion Drive Assembly, a Vehicle and a Method for changing the Offset of a Bogie Axle Drive Assembly - Google Patents

Abstract

An offset adaptor 30 is provided which is able to provide for an offset between a pivot axis of an axle structure 26 and a connection point at a bogie assembly 28, such that a front and a rear ground engaging means 22 on the bogie assembly 28 act on the ground with different levers.

Description

OFFSET ADAPTOR, A PROPULSION DRIVE ASSEMBLY, A VEHICLE AND A

METHOD FOR CHANGING THE OFFSET OF A BOGIE AXLE DRIVE ASSEMBLY Field of the Invention This invention relates to an offset adaptor, a propulsion drive assembly, a vehicle and a method for changing the offset of a bogie axle drive assembly.

Background of the Invention The use of bogie axles is well known in forestry machines and construction machines, see as examples WO 2012/123630 A1, US 5417297 A or DE 41 20 801. Such bogie axles provide for an equal load distribution and hence an equal transmittal of driving force to the ground in ideal conditions only. Yet, when accelerating the vehicle or when resistance is found at one of the wheels of a bogie, the bogie tends to rise with one of its arms and loses grip on the ground.

US 2194323 A discloses an offset assembly of a vehicle according to the preamble of claim 1. The offset assembly comprises a bogie assembly with ground engaging wheels on each side of the vehicle.

The problem this invention is based on is seen in the need to provide a better = 25 transmittal of propulsion force. & 3 Summary of the Invention

N E This problem is solved in an innovative way by means of the teaching of claim 1, 6, 11 = 30 and 12, whereas advantageous features further developing the invention are given in D the claims related to them.

S Such an offset adaptor is an independent device, which can be installed at the assembly line of a vehicle or as a retrofit unit to already delivered vehicles. The input

-2- and output shafts may be short shafts or even just gears with outer and/or inner splines and preferably have a short axial dimension, so that the adaptor does not add more to overall dimensions than necessary. The kind of input and output shaft will be chosen according to the drive components to be connected to. I.e. they may be connected to upstream and/or downstream drives by gears, claws, flanges, etc. When the input shaft is coaxial with the bearing, any pivot movement of the offset adaptor about the input shaft will be without stress in the system. The interface may be designed to be connected at counter interfaces by welding, positive locking, bolting, force locking or any other technology. The gears could have any sort of teeth, like axial, worm, slanted or other teeth. The bearing could be of a big diameter ring slidingly received in a housing, notch or grove or a bearing race carried by balls, needles or rolls. The interfaces may be simple flanges in metal plates with sets of holes for bolts or with studs to be fastened at the counter interface. Connecting interfaces via bolts is a simple and fast way. If also the second interface is provided with or formed as a bearing, the offset adaptor can pivot at both of its connecting points. Both bearings may be big thrust bearings with rings, gliding in a grove, as well as roller bearings. Said ring or a race of the bearing may be one part with the interface as well as releasably connected to it. In a very sophisticated version, the interfaces with the bearings are formed as a single casted or forged and machined part. While a bearing is designed to allow a relative movement, sometimes circumstances appear, in which said movement shall be avoided or controlled, which is possible by means of arresting means. Such arresting means could be mechanical locks, splines, = 25 — keys, etc. pushed into a recess of a fixed part, friction liners of brakes or clutches, N electromagnetic clutches etc. 2 N The offset adaptor may also serve as sort of a downstep or upstep transmission if its E input shaft and output shaft have different diameters in their meshing section. It would = 30 even be possible using a planetary gear in connection with the input and output shaft.

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R > Vehicles used in construction, agriculture or forestry applications are operated mostly on uneven terrain. At the same time they have a heavy weight by itself or when carrying loads and bogie axles with wheels or tracks around wheels are used to cope with these

-3- problems.

In order to drive propulsion power to the ground in an optimum way, even when working on slopes, in mud, etc. an offset between the center of the bogie axle structure to the pivot axis has the effect, that a rising effect known from bogie axles (see above mentioned prior art) is under control.

The extension and direction of the offset will be chosen according to the application, load distribution of the vehicle, etc.

With that offset the bogie is still able to pivot about the axle structure extending transverse to the longitudinal axis of the vehicle as a solid unit, but the length of the lever from the front wheel to the pivot axis and the rear wheel to the pivot axis will differ and so will the weight distribution and accordingly the drive torgue.

As both interfaces and with them the pivot axis of the offset adaptor remain between the pivot axes of the ground engaging wheels, unlike in prior art devices, no external forces are needed to keep the bogie in an operative condition.

When in addition the second interface is connected vertically pivotally to the bogie axle — structure, a better torque distribution is achieved as well as adaptability to the ground contour.

The pivot movement between the offset adaptor and the axle structure at one end and/or the pivot movement between the offset adaptor and the bogie assembly at the other hand may happen freely and unobstructed depending on the ground contour, but it could also be controlled actively by mechanical links, by driven actuators or other means.

In order to achieve a certain load distribution of the ground engaging means on the o 25 = ground, pivot movement of the bogie axle versus the offset adaptor may be blocked N through arresting means as described before.

Such arresting means could be 3 mechanical stops, locks, mechanical or friction type brakes or clutches, abutments etc; 2 their function could be controlled or always be present in a given location or situation. z = 30 In order to dampen shocks coming from driving over rough ground, a resilient D suspension device may be used between the offset adaptor and the bogie axle > structure.

Such a resilient suspension device could be a rubber or elastic cushion, a radial metallic spring device or similar.

-4- As depending on the application of the propulsion drive assembly an offset may be needed in different directions, a bogie axle structure mirror image design along a plane through its connection areas can be tilted vertically about 180 degrees, such that its short or long end with respect to the pivot axis may be reversed. This gives flexibility in the production place as well as in later use and reduces the variety of prefabricated components needed. Vehicles used in forestry, construction and agriculture are of very different kinds with different numbers and kinds of ground engaging means, load space vs. no load space, application on slopes or even ground, etc. which is considered respectively by placing the offsets as required. The only requirement is that pairs of propulsion drive assemblies, i.e. those opposite to each other with respect to a longitudinal axis of the vehicle have the same offset. The offset of the pairs with respect to pairs in front or behind may be the same or opposite, or there may be none versus one with an offset.

Brief Description of the Drawings In the following one embodiment of the invention is described in more detail and in relation to the drawing. It is shown in: Fig. 1 a vehicle in side view, Fig. 2 another vehicle in side view, Fig. 3 a propulsion drive assembly in top view with an offset to the rear, Fig. 4 the propulsion drive assembly in side view with an offset to the rear, o 25 Fig. 5 a schematic of the drive line in the propulsion drive assembly with an N offset to the front, 3 Fig. 6 a perspective view of an axle structure and a bogie assembly with an 2 offset adaptor and with an offset to the front, E Fig. 7 the offset adaptor in perspective view with an offset to the front, = 30 Fig. 8 another offset adaptor in top view and a cross section, D Fig. 9 the propulsion drive assembly in a first state in side view, > Fig. 10 — the propulsion drive assembly in a second state in side view and Fig. 11 the propulsion drive assembly in a third state in side view.

-5- Detailed Description of the Invention A vehicle 10 shown in figure 1 is of the kind of a forwarder, used to transport logs in a forest. Similarly figure 2 shows a vehicle 10 of the kind of a forest harvester, used to cut standing trees. Both vehicles 10 comprise a chassis 12 with an articulation 14 in about the longitudinal center, a cab 16 on the front portion of the chassis 12, an engine compartment 18 adjacent to the cab 16 on either the front or the rear portion of the chassis 12, a crane assembly 20 received horizontally rotatable on the chassis 12, ground engaging means 22 to support the chassis 12 on the ground and a propulsion drive assembly 24 connecting the ground engaging means 22 to the chassis 12.

The vehicle 10 is typically for off-road use and could also be a construction machine, an agriculture machine, a full-tree harvester, etc.

The chassis 12 is in the form of a welded sheet metal structure and could also be of the non-articulated type. Instead of a separate structure, the chassis 12 could as well be composed of the engine (not shown) and components of the propulsion drive assembly 24 forming an elongate body as this is known from tractors.

The ground engaging means 22 are shown as wheels, but could also be tracks slung around drive and idler wheels and as another alternative, a steel or rubber track could be slung around the wheels shown.

According to figures 3 ff. Each propulsion drive assembly 24 comprises an axle o 25 structure 26 and at least one bogie assembly 28 at each side of the vehicle 10 N connected to the axle structure 26 via an offset adaptor 30.

2 2 Except the offset adaptor 30 the vehicles 10 described so far are equivalent to E-series E forwarders and forest harvesters of JOHN DEERE and need no further description.

= 30 D The axle structure 26 comprises a housing 32 connected in a fixed relationship to and > under the chassis 12. Instead of, the housing 32 could also be pivotable about a longitudinal axis and/or spring suspended. The axle structure 26 extends with its main axis transverse to the longitudinal direction of the vehicle 10 at least until or even

-6- beyond the lateral border of the chassis 12. The housing 32 could be made as either of acast, a welded sheet metal structure or a steel tube or similar or a combination thereof.

Inside the housing 32 is normally provided a differential gear 34 (not shown in detail), driven by a drive shaft 36 and driving a lateral output shaft 38 at each side, extending towards the offset adaptor 30. The housing 32 terminates at each lateral end with a bearing 40. Said bearing 40 is in the form of a thrust bearing with a ring 42 rotating in a housing 44, whereas the ring 42 is axially immobile and has holes (not shown) to receive bolts (not shown). The ring 42 may rotate in a vertical plane along the longitudinal axis of the vehicle 10 and about a central axis of the output shaft 38. The differential gear 34 and the output shaft 38 could be replaced by hydraulic or electro motors, though.

The bogie assembly 28 is in the form of ordinary bogie axles, as they are used in above mentioned John Deere forestry machines or other forestry machines. Such a bogie assembly 28 has an elongate housing 46 made of cast or welded steel sheet metal with a hub 48 in the center and a final drive 50 at each housing end area. While the hub 48 faces the axle structure 26, the final drives 50 are provided on the other side of the housing 46. Each final drive 50 receives rotatably a hub 52 for a ground engaging means 22, normally in the form of a wheel. Parallel center axes 84 and 86 extend through the hubs 48 and 52, latter in the respective end areas of the housing 46. Inside the housing 46 is provided a set of spur gears 54, in the case shown with one in the center and three to each side; also provided in the housing 46 is any sort of lubrication o 25 means. The last spur gear 54 is one part with a shaft for driving the hub 52 of the N ground engaging means 22 via another gear. All this is customary in the art and could 3 also be replaced by a chain drive or similar. Actually a mechanical drive is not required 2 at all, but electro or hydraulic motors could be used in the final drives 50 instead. While E in the shown embodiment the final drives 50 are offset from the housing 46 towards the = 30 ground, seen at an installed bogie assembly 28, the housing 46 and final drives 50 could also be arranged without said offset and thus mirror imaged with respect to a > center plane through the rotational axes 86 of the hubs 52. The same applies in the case of the hub 48, which instead of being offset to the upper side, could be in the center.

-7- The offset adaptor 30 in its most simple form contains a carrier 56 with an axle side interface 58 containing a set of fastening means and a bogie side interface 60, with another set of fastening means, both being offset to each other in the direction of the longitudinal plane of the carrier 54. In the embodiment shown, each interface 58, 60 is formed as a series of holes arranged on a circular line, which allow bolts (not shown) to reach through and get fastened in respective sets of holes in the ring 42 and the hub 48 respectively.

As shown, the carrier 56 has rounded edges to follow the silhouette of the connecting surfaces at the axle structure 26 and the hub 48. In the inner area of carrier 56 is provided a big aperture 62, which gives room for a drive line 64, which may be of the mechanic, electric or hydraulic type.

In the embodiment shown a mechanical drive line 64 is chosen, which comprises a housing 66 with a flange 68, an input gear 70 and an output gear 72. Input gear 70 and output gear 72 are arranged coaxially, mesh constantly and are journalled rotatably in the housing 66. Instead of a constant mesh, also a clutch may be provided between them.

The gears 70, 72 are splined internally to receive the output shaft 38 and a shaft to the center spur gear 54 respectively.

The flange 68 and with it the housing 66 is bolted in ordinary manner to the hub 48 of the bogie assembly 28 and extends in a plane parallel to that of the carrier 56. In a case without mechanical drive of the bogie assembly 28, different combinations of interfaces 58, 60 could be provided to achieve different offset distances.

Also, housing 66 with its components could be missing and be replaced by electro cables or hydraulic hoses. o 25 Ina further development of what is described above and shown in figures 1 to 7, hub 48 N in housing 46 of the bogie assembly 28 could as well be formed as a bearing 74 3 comparable to and rotating in a plane parallel to that of bearing 40. 00 E In this version of an offset adaptor 30 the carrier 56 is less formed like a plate, but like a = 30 housing made of cast.

Said carrier 56 is vertically rotatably received by means of a ring 42 on or in housing 44 of axle structure 26, comparable to the first embodiment.

On the > opposite side the carrier 56 is provided with (connected or formed) a ring 78 to be received rotatably in the hub 48 in housing 46 of the bogie assembly 28. Said carrier 56 also contains non-referenced bearings to rotatably receive input and output gears 70,

-8-

72. In this embodiment input gear 70 is formed as a single piece with output shaft 38 and output gear 72 is formed as a single piece with a drive shaft of the center spur gear

54. Interfaces 58 and 60 in this case are formed by recipients of the rings 42 and 78 formed in or attached to the carrier 56 and both provide for a pivot movement between the offset adaptor 30 and the axle structure 26 at one side and the bogie assembly 28 at the other side. Arresting means 92 are provided, surrounding a hub 94 on the carrier 56 and being connected to the housing 46 of the bogie assembly 28. Said arresting means 92 are able to lock bearing 74 in either a defined or at any position. Such arresting means 92 could be disc brakes, mechanical stops, hydraulically or electrically operated keys entering recesses in a respective counterpart, like the ring, or similar. Figure 8 shows bores 96 for inserting axially moveable lock, engaging in recesses in the carrier 56. In addition a shock absorber for dampening suspensing forces could be provided in the arresting means 92 or between them and the carrier 56.

Based on the above description of the structure the assembly and function can be described as follows starting from an embodiment with a mechanical drive as shown in the drawing.

Reference is taken to figure 3 showing the propulsion drive assembly 24 of a vehicle 10 inthe form of a forwarder, the forward driving direction of which is indicated by the arrow. In contrast to the propulsion drive assembly 24 with an offset adaptor 30, the upper half of figure 3 shows the situation in the prior art without an offset adaptor 30 and where the bogie assembly 28 pivots about a pivot axis 80, which is also the center axis of the axle structure 26. In the case shown in the upper half both ground engaging o 25 means 22 have the same distance to the pivot axis 80 and in an ideal state both carry N the same load and the same torgue is transferred to them. This known version is only 3 shown to make evident the difference to the device using the offset adaptor 30; in reality 2 both cannot be used together. In the lower half of figure 3 is shown the propulsion drive E assembly 24, in which the offset adaptor 30 is inserted between the axle structure 26 = 30 and the bogie assembly 28. As a result and depending on the distance between the two D interfaces 58, 60 the bogie assembly 28 is moved to the rear of the vehicle 10 and an > offset 82 is created between pivot axis 80 and the center axis 84 of hub 48. As a conseguence of said offset 82, the distance between center axes 86 of the front and rear ground engaging means 22 and the pivot axis 80 changes as well and a short pivot

-9- arm 88 is created at the front, whereas a long pivot arm 90 is created at the rear. With interface 58 of carrier 56 being bolted to the ring 42 of the bearing 40 in the axle structure 26, the bogie assembly 28 bolted to the carrier 56 at the bogie side interface 60 is able to pivot about pivot axis 80 eccentrically. Said offset 82 is identical to the distance between the longitudinal axes of the input gear 70 and the output gear 72, which avoids any jamming, when the bogie assembly 28 pivots about pivot axis 80. A practical ratio between long and short pivot arm (distance between rotation and front wheel axes : distance between rotation and rear wheel axes) in standstill of vehicle 10 is maximum around 30:70 or 25:75 depending on bogie geometry; but this nos. are not meant to be limiting. If for some reason limits are reached a mechanical limit may be applied, such as a frame or bogie stopper, to limit the lifting of any of the ground engaging means 22 or overturning of the bogie assembly 28. In any way, pivot axis 80 is always between axes 86 the ground engaging means 22 are rotating about.

Whether the offset is to the front (figures 5 to 7) or to the rear (figures 3 and 4) of the vehicle 10 depends on the situation in which it operates, like up- or downhill operation, load distribution along the longitudinal axis of the vehicle 10, operation on even and potentially paved ground, versus muddy ground, main driving direction etc. On a vehicle 10intheform of a forwarder shown in figure 1, the front bogie assembly 28 may be offset to the front and the rear bogie assembly 28 may be offset to the rear in order to achieve a more equal load during driving on the 2", 3 and 4% pair or ground engaging means 22 counted from the front. Typically and independent whether the vehicle 10 is formed as a forest harvester or a forwarder it appears advantageous having the front o 25 bogie assembly 28 offset to the front, as this avoids pushing into the mud, when driving N forward. In the case of a bogie assembly 28, which is — as explained above — of mirror 3 image along its longitudinal axis, the installed bogie assembly 28 could be pivoted in a 2 vertical plane about 180 degrees, when the vehicle 10 is lifted an appropriate amount, E which allows adjusting the vehicle 10 to a different application and makes it easier also = 30 inthe assembly in the factory. 3 > The embodiment shown in the figures 8 to 11 follows the same principle; however it may pivot in bearing 74 in addition to bearing 40. While bearing 40 allows a constant pivot movement to let the bogie assembly 28 follow the ground contour with both

-10 - ground engaging means 22 on the ground, bearing 74 allows a pivot movement between housing 46 of the bogie assembly 28 and the offset adaptor 30 between a front offset position shown in figure 9 and a rear offset shown in figure 11 via a center position shown in figure 10. Providing a lock of the bearing 74 in the center position is an option. Moving the bogie assembly 28 between and into the individual positions, depending on the operational needs could happen via external motors, like linear or rotational hydraulic motors. However, modern vehicles 10 with separate propulsion drive assemblies 24 for the front and the rear are able to drive one propulsion drive assembly 24, e.g. the rear one, only resulting in an idle stage of the other propulsion drive assembly 24, e.g. the front one. When being in the idle stage and with open arresting means 92, the idling bogie assembly 28 is exposed to the friction on the ground and will rest in its position, while the vehicle 10 with its chassis 12 moves. This movement will pivot the bogie assembly 28 via the center position to the other end position. If it deems necessary, anyway available brakes for the ground engaging means 22 of said idling propulsion drive assembly 28 can be activated by an appropriate control to create more friction on the ground.

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Claims (12)

-11 - Claims

1. Offset adaptor (30), characterized by having: a) a first interface (58) designed to be connected to a bearing (40) in or designed to be a bearing for an axle structure (26), b) a second interface designed to be connected to a bogie assembly (28), c) an input shaft (70), and d) an output shaft (72) meshing with and being radially offset to said input shaft (70), and the output shaft (72) being coaxial with a pivot axis (80) of the bearing (40).

2. Offset adaptor according to claim 1, whereas at least one of the interfaces (58, 60) is formed as a flange with means for a connection by bolts.

3. Offset adaptor according to claim 1 or 2, whereas the second interface (60) is formed as or provided with a bearing for a pivot movement with the bogie assembly (28).

4. Offset adaptor according to either of the preceding claims, whereas a bearing (74) attached to or formed in the second interface (60) is provided with arresting means (92).

5. Offset adaptor according to one or more of the preceding claims, whereas the meshing input and output shaft (70, 72) have different diameters for creating a o 25 down- or upstep transmission. & 3 6. Propulsion drive assembly (24) of a construction, agriculture or forestry vehicle 2 (10) comprising: E a) at least one axle structure (26) oriented transverse to the longitudinal axis = 30 of the vehicle (10), and D b) a bogie assembly (28) with ground engaging means (22) in the form of at > least two ground engaging wheels or a ground engaging track routed over at least two wheels on each side of the vehicle (10), characterized in that the propulsion drive assembly further comprises:

-12 - c) an offset adaptor (30) with two interfaces (58, 60) offset in the longitudinal direction of the vehicle (10), whereas one interface (58) is pivotally attached to the axle structure (26) and the other interface (60) to the bogie assembly (28) and whereas both interfaces are located between the axes (84, 86) of hubs (48, 52) receiving the ground engaging means (22).

7. Propulsion drive assembly according to claim 6, whereas the second interface (60) is pivotally attached to the bogie assembly (28).

8. Propulsion drive assembly according to claim 6 or 7, whereas the bearing (74) connected to or formed at the second interface (60) is provided with arresting means (92).

9. Propulsion drive assembly according to one or more of claims 6 to 8, whereas the bogie assembly (28) is resiliently suspended by the second interface (60).

10. — Propulsion drive assembly according to one or more of claims 6 to 9, whereas the bogie assembly (28) has a housing (46) with a hub (48) on one side to be connected to the second interface (60) and at least two hubs (52) on the opposite side for ground engaging means (22), and whereas the housing (46) with the hubs (46, 48) is of mirror image design along a plane through the centers of all hubs (46, 48).

11. Vehicle, characterized by having pairs of propulsion drive assemblies according o 25 to one or more of the claims 6 to 10 behind each other in the driving direction, N whereas: 3 a) only one pair of the propulsion drive assemblies (24) is offset, or 2 b) both pairs of propulsion drive assemblies (24) are offset in the same E direction, or = 30 c) both pairs of propulsion drive assemblies (24) are offset in opposite D directions.

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12. Method of changing the offset of a bogie assembly (28), characterized by the bogie assembly (28) being pivotally attached to and by means of an offset

- 13- adaptor (30) to a transverse axle structure (26) and bearing ground engaging means (22) on a vehicle (10) with another ground engaging means (22), in the method the offset of the bogie assembly (28) being changed by the steps of moving the vehicle (10) with the other ground engaging means (22) only and thereby exposing the ground engaging means (22) of the bogie assembly (28) to the resistance created by the ground over which the vehicle (10) is moving.

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