WHEEL SUSPENSION DEVICE AND METHOD FOR MOUNTING THE DEVICE

Abstract: This invention relates to a method of modifying the front carriage of a transport vehicle of the light type, its front carriage having a transversal girder, at each end of which the lower portion of an essentially vertically directed helical spring is fastened, and an upper transversal link, at the inner end portion of which the upper end portion of the helical spring is fastened. According to the invention the method is characterized by the following steps: the helical springs are loosened and removed; an air spring unit (9, 10) is placed at each of the positions where the helical springs have been placed and are fastened in the mentioned front carriage; each of the air spring units (9, 10) is connected via an air tube with a level indicator (18), which in its turn is connected with an air tank of the vehicle, the level indicator (18) sensing and adjusting the height of the vehicle over the ground. The invention also relates to an assembly for carrying out the method.

Description: Wheel Suspens ion Device and Method for Mounting the Device This invention relates to a method of modifying the front carriage of a transport vehicle of the light type, its front carriage normally having a transversal girder, at each end of which the lower portion of an essentially vertically directed helical spring is fastened, and an upper transversal link, at the inner end portion of which the upper end portion of the helical spring is fastened. This type of front carriage is common today on transport vehicles of the light type, i.e. up to a weight of about 5 tons, which vehicles are used for freight and passenger transportation. In recent time there have arisen wishes that these light-type vehicles for passenger transportation shall be provided with an air spring system in the front carriage, which should make possible for the vehicle to be raised and lowered, whereby stepping into and out of the vehicle should be facilitated. This invention intends to meet with these wishes and to provide light-type transport vehicles with an air spring system in its front carriage. This has been made possible by a method of the kind mentioned by way of introduction, which comprises the steps mentioned in the following claims. A preferred embodiment of an arrangement for making a carrying out of the new method possible shall be described more closely below with reference to the accompanying drawing, where Fig. 1 shows a part of an existing front carriage for a light-type transport vehicle, Fig. 2 and 3 show the new arrangement, this one being seen obliquely from above from the one and the other side, respectively. Referring to Fig. 1 is shown there a part of an existing front carriage. This one comprises a transverse girder 1, to both end portions of which the lower part of a helical spring 2 is fastened. Furthermore, the front carriage has an upper 3 and a lower slewing bracket 4, both of which being articulately connected with the girder 1. The outer end portions 5, 6 of the two slewing brackets are connected with the fastener 7 of the vehicle for the front wheel. The inner end portion of the upper slewing bracket constitutes a fastener for the upper part of the helical spring 2. As appears from Fig. 1, the helical spring 2 has an essentially vertical extension. In Figs. 2 and 3 is shown the new air spring arrangement that shall replace the helical springs 2 in the known front carriage, which means that the two helical springs are taken loose. The new air spring arrangement comprises two air spring units 9, 10, which are essentially alike, and each one of which shall replace a helical spring 2 in the existing front carriage. Each unit 9, 10 comprises a lower plate 11, which on its underside has a portion 12, projecting downwards, which is intended to be fastened on that place of the girder 1, where the lower part of the helical spring has been fastened. The unit further comprises an upper plate 14, provided with an upwards-projecting, central bolt 13, which plate is intended to be fastened to the inner end portion 8 of the upper slewing bracket 3. Between these two plates is a rubber bellows 15 fastened, the two end portions of which being fastened on the topside of the plate 11 and the underside of the plate 14. The rubber bellows, in a usual way, can be filled with air, whereby the distance between the plates 11, 14 increases, or be evacuated of air, whereby the distance between the plates is reduced, via an air nipple 16, which is arranged on the topside of the upper plate 14, and which in a mounted condition is in connection with an air tank. This means that when the front carriage of the vehicle shall be lowered, air is let out of the air bellows via the nipple 16, and when the height of the front carriage over the ground shall be increased, air is let into the air bellows from the air tank via the nipple 16. On the lower plate 11 of the one air spring unit 10 there is arranged a fastener 17 for a mechanical level indicator 18 of known type, which is intended to sense and adjust the height of the vehicle over the ground. This level indicator is in a known way connected partly with the air tank, partly with respective air bellows 15 via the air nipple 16. According to this embodiment the two air spring units 9, 10 are connected with each other by a rod 19, which is adjustable in its longitudinal direction and is fastened to a bar 20, projecting outwards from the upper plate 14 of each unit. From the rod 19 projects downwards an essentially vertical rod 21, which at its lower portion is connected with the level indicator 18 via a lower bar 22. Due to the mentioned design with the rod 19, connecting the units 9, 10 with each other, and its connection with the level indicator 18, that advantage is achieved that the movements of the suspension between the two units are balanced out, whereby the comfort of the vehicle is improved. The modification of the front carriage of the transport vehicle is made in the following way: The two helical springs are loosed and removed, whereafter the first air spring unit is fastened on the former place of the first helical spring, whereas the second air spring unit is fastened on the former place of the second helical spring. To connect the two air spring units with a rod being in connection with a mechanical level indicator, as has been described above, is not necessary but has appeared to be advantageous. Thus, this embodiment can be regarded as a further development of the invention. Besides the previously mentioned advantages like the ability to raise and lower the vehicle, the application of the air spring units means that the wheel suspension of the vehicle becomes better with a more soft riding comfort as a result. The invention is not limited to the described embodiment but can be modified within the scope of the following claims. Thus, the mechanical level indicator could be replaced by an electronic level indicator.

Claims: Claims 1. A method of modifying the front carriage of a transport vehicle of the light type, its front carriage having a transversal girder, at each end of which the lower portion of an essentially vertically directed helical spring is fastened, and an upper transversal link, at the inner end portion of which the upper end portion of the helical spring is fastened, characterized by the following steps: - The helical springs are loosed and removed; - An air spring unit (9, 10) is placed at each of the positions where the helical springs have been placed and is fastened in the mentioned front carriage; - Each of the air spring units (9, 10) is connected via an air tube with a level indicator (18), which in its turn is connected with an air tank of the vehicle, the level indicator (18) sensing and adjusting the height of the vehicle over the ground. 2. A method according to claim 1, characterized in that the upper portions of the two air spring units (9, 10) are connected by a rod (19), which in its turn is connected with the level indicator (18) via one or more other means (21 , 22), whereby the movements of the suspension of the two units (9, 10) are balanced out. 3. An air spring unit useable for carrying out the method according to claim 1 or 2, characterised by the following features: - The unit (9, 10) comprises a lower (11) and an upper plate (14) between which an air bellows (15) is fastened, which can be blown up as well as evacuated; - The unit (9, 10) is at its top portion provided with a means (16) for introducing air into and taking out air from, respectively, the air bellows, which means (16) is connected with an air tank via a level indicator (18). 4. A unit according to claim 3, this one being intended to be mounted in the front carriage of a vehicle, characterized in that the lower plate (11) has a downwardly projecting portion (12), which is intended to fit into a cup-shaped recess in the one end portion of a transversal girder (1) of the front carriage of the vehicle, and that the upper plate (14) has a centrally, upwards projecting bolt (1) for fastening of the unit in an upper slewing bracket (3) of the front carriage of the vehicle. 5. An arrangement useable for carrying out the method according to claim 1 or 2, this one comprising two air spring units according to claim 3 or 4, characteri z e d in that the upper portions of the two air spring units (9, 10) are connected by a rod (19), which in its turn is connected with a mechanical level indicator (18) via one or more means (21, 22), and that the level indicator is arranged on the one unit (9, 10). 6. An arrangement useable for carrying out the method according to claim 1 or 2, this one comprising two air spring units according to claim 3 or 4, characteri z e d in that at least the one air spring unit (9, 10) is provided with an electronic level indicator.

Inventors: SJOELUND ANDERS, SJOELUND, ANDERS
Applicants: SJOELUND ANDERS, SJOELUND, ANDERS
Application year: 1999
Main classification: B60G3
IPC codes: B60G3, B60G17