APPARATUS AND METHOD FOR HANDLING TWIN WHEELS OF A VEHICLE

Abstract: The invention relates to an apparatus for handling twin wheels of a vehicle. The apparatus comprises a frame structure (1-3), two pairs of support members (10-11 and 12-13), and a hydraulic lifting arrangement comprising at least a hydraulic actuator (8) for lifting the pairs of support members (10-11 and 12-13). The pairs of support members (10-11 and 12-13) are arrayed in two support member pairs (10-11 and 12-13) that can be lifted separately, the hydraulic lifting arrangement comprises first hydraulic lifting means (14, 15) connected to the hydraulic actuator (8) and coupled to lift the first pair of support members (10-11) and second hydraulic lifting means (16a-16f) coupled to lift the second pair of support members (12-13), and the first and second hydraulic lifting means (14, 15, 16a-16f) are connected to a common hydraulic pressure generated by the hydraulic actuator (8).

Description: Apparatus and method for handling twin wheels of a vehicle The present invention relates to an apparatus for handling twin wheels of a vehicle, in particular for removing twin wheels from a shaft of the vehicle and for installing them on the shaft, the apparatus com¬ prising a frame structure, two pairs of support mem¬ bers, and a hydraulic lifting arrangement comprising at least a hydraulic actuator for lifting the pairs of support members. The invention also relates to a method for handl¬ ing twin wheels of a vehicle, in particular for remov¬ ing twin wheels from a shaft of the vehicle and for installing them on the shaft, in which method the twin wheels are handled with a lifting device comprising two hydraulically liftable pairs of support members while the shaft of the vehicle is freely supported, and in which method the twin wheels are lifted onto the support of the pairs of support members of the lifting device. By twin wheels is meant a dual wheel combination comprising two wheels attached together at their disc wheels with wheel studs, and a wheel hub, a brake disc, and braking means, such as ABS braking means. The apparatus and method of the invention are suitable for handling twin wheels of various vehicle types in repair work, such as brake repair, in connec¬ tion with which the twin wheels must be removed from a shaft of the vehicle and after the brake repair replaced on the shaft. A vehicle in this context means a truck, bus, van, forklift, tractor, motorized equip¬ ment, or aircraft, for instance. The heavier the twin wheels to be handled with the apparatus, the more indispensable the apparatus of the present invention. The apparatus of the invention is employed when twin wheels of a vehicle must be detached from a shaft of the vehicle or fitted on the shaft for repair or maintenance, for example. In employing the apparatus, the vehicle shaft is jacked off, for example, in other words, the shaft is freely supported. The weight of vehicle twin wheels is so large that to handle them with mere manpower may be hazardous to the person carrying out the work. The weight of twin wheels is in the range 200-500 kg, depending on the vehicle size. Normally, brake repairs on vehicles may only be carried out by repair shops approved by the authorities, i.e. by the Central Motor-Vehicle Regis¬ ter, and it is a requirement that the repair shop has a twin-wheel lifter, i.e. an apparatus for handling twin wheels. The handling of twin wheels is an exacting task. It is vital to be able to handle twin wheels of a vehicle easily, so that the gaskets of the twin wheels will not be damaged. It is typical of the pair of tyres in twin wheels that the tyre diameters may differ as much as 30 mm, in other words, the difference between the tyre radiuses may be as great as 15 mm. This is mainly a result of the fact that roads are normally convex, and thus the inner tyre will wear more rapidly. The differences in tyre radiuses of twin wheels may also ensue from the fact that a worn or failed tyre has been replaced by a new tyre that is not worn, and thus the twin wheels comprise a new tyre with a greater diameter and an older tyre having a smaller diameter on account of wear. The fit of twin wheels on a shaft is very tight, and the twin wheels must be removed from the shaft and mounted thereon precisely in the direction of the shaft, for otherwise the gaskets and ABS braking means may be damaged. It is known in the art to perform the exchange and other kinds of handling of twin wheels of a vehicle, a truck for instance, using accessories, i.e. lifting means. Known devices are disclosed for example in German Patent 2 005 980, U. S. Patent 3 951 286, U. S. Patent 2 806 615 and U. S. Patent 2 670092 (Re 23 923). The drawbacks of these known devices reside in carrying out the lifting of the pairs of support mem¬ bers. In the prior art solutions, the halves of the separate pairs of support members disposed on the same side of the apparatus are in fixed mechanical connec¬ tion with one another, at least when the support mem¬ bers are lifted. These known apparatuses and methods cannot carry out an independent hydraulic lifting operation for the different pairs of support members. For the above reasons, the problem arises in connection with removing the twin wheels from the shaft that while the twin wheels of the vehicle still repose on the shaft, the support members of the lifting means lift one tyre of the twin wheels too high, wherefore the twin wheels tend to be inclined into a position devi¬ ating from the direction of the shaft of the vehicle. In consequence, when the twin wheels are withdrawn, there is a danger that gaskets or braking means included in the shaft are broken, since the withdrawal movement does not have the direction of the shaft. The prior art solutions are also time-consuming in that they are labour-intensive, since the person carrying out the work must pay attention to several factors and possibly lay wooden wedges or other bodies of different height to align the twin wheels in the direction of the shaft of the vehicle. Similar problems are also encountered when the twin wheels are again mounted on the shaft, since the twin wheels should also be lifted to an inclination corresponding to the inclination of the shaft of the vehicle. The prior art devices are also complex in construction, are awkward to use, and require a wide variety of special parts, thus being costly to manufacture. In certain prior art devices, the pairs of support members are incorporated in a common mechanically inclinable structure which aims at adjusting the inclination of the twin wheels. Yet such devices are incapable of eliminating, adequately and with sufficient simplicity, the problems presented by variance in diameters of the tyres of twin wheels and by the inclination of the working platform or ground, as the lifting/lowering of one pair of support members will lower/lift the other pair of support members. It is an object of the present invention to pro- vide an apparatus for handling twin wheels of a vehicle, avoiding the problems and drawbacks of the prior art arrangements and enabling detachment, mount¬ ing, and other kinds of handling of twin wheels in an effective, easy and rational way. This object is achieved with the apparatus of the invention, which is characterized in that the pairs of support members are arrayed in two pairs of support members that can be lifted separately, that the hydr¬ aulic lifting arrangement comprises first hydraulic lifting means connected to the hydraulic actuator and coupled to lift the first pair of support members and second hydraulic lifting means coupled to lift the * second pair of support members, and that the first and second hydraulic lifting means are connected to a common hydraulic pressure generated by the hydraulic actuator. The method of the invention is characterized in that in the method the hydraulic lifting of the pairs of support members is performed by a common hydraulic pressure in such a way that when the first pair of sup- port members engages the lower surface of the first wheel of the twin wheels, the lifting of the pair of support members is discontinued self-actuatedly and the hydraulic pressure is directed to lift the second pair of support members until that pair of support members engages the lower surface of the second wheel of the twin wheels, whereafter the twin wheels are lifted onto the support of the pairs of support members by at least slightly lifting each support member pair. The apparatus and method of the invention provide several advantages. The apparatus and method of the invention eliminate problems arising from the inclina¬ tion of working platforms or ground and from the uneven wear of the tyres of twin wheels. The invention affords considerable advantage in speeding up the work perform¬ ance, since when a wheel is to be removed, the appar¬ atus enables positioning of the pairs of support mem¬ bers in such a way that the lifting will be directed to each wheel individually, as a result of which the twin wheels are supported by the support members of the apparatus exactly in the direction of the shaft, thus permitting removal of the twin wheels from the shaft without the gaskets or the ABS braking means becoming damaged. Similar advantages are achieved when the twin wheels are again mounted on the shaft. With separate pairs of support members connected to a common source of hydraulic pressure, it is accomplished that when a pressure is pumped with the hydraulic pump, the appar¬ atus will position the pairs of support members on the wheels, one pair of support members at a time. Further¬ more, the person carrying out the work can, if he so wishes, incline the twin wheels in the direction of the shaft by lifting or ' lowering the other pair of support members. The arrangement in accordance with the inven- tion is also of a uncomplicated construction and can be installed at reasonable cost. The arrangement of the invention is also capable of centering the twin wheels well. The apparatus and method are easy to use. The different structural parts of the apparatus are of such a construction that the apparatus is open at the disc wheel, which enables hub transmission and unobstructed dismounting and mounting of the wheel bearings. The preferred embodiments of the invention enhance the above advantages. In the following the invention will be explained with reference to the accompanying drawings, in which Figure 1 is a forward perspective view of the apparatus seen obliquely from the front, Figure 2 is a top view of the apparatus, and Figure 3 is a side view of the apparatus with twin wheels. With reference to Figures 1-3, the apparatus com¬ prises a frame structure 1-3. Part 1 represents the middle portion and parts 2-3 represent side portions of the frame structure. The apparatus also comprises underwheels 4. A vehicle shaft wherefrom the twin wheels are to be dismounted or removed or a vehicle shaft on which the twin wheels are to be installed is denoted by reference numeral 5. The twin wheels com- prise wheels 6 and 7, each of which comprises a tyre 6a, 7a and a disc wheel 6b, 7b. The twin wheels also comprise a hub and a brake drum. The apparatus comprises a hydraulic actuator 8 having a handle 8a. The hydraulic actuator 8 is prefer- ably a hydraulic pump. The actuator 8, preferably a hydraulic pump, comprises a pressure relief means 8b, which is preferably a valve or an equivalent means. The apparatus comprises support members 10-13 whereupon twin wheels 6, 7 are supported, i.e. lifted, with the hydraulic actuator 8. It is to be seen from the figures that four support members arrayed in two pairs 10-11 and 12-13 are provided. The hydraulic actuator 8 forms part of a hydr¬ aulic lifting arrangement. The hydraulic lifting arran- gement further comprises first hydraulic lifting means 14-15 connected to the actuator 8 and coupled to lift the first pair of support members 10-11. The hydraulic lifting arrangement also comprises second hydraulic lifting means 16a-16e coupled to lift the second pair of support members 12-13. The first hydraulic lifting means 14-15 and second hydraulic lifting means 16a-16e are connected to a common hydraulic pressure generated by the hydraulic actuator 8. The support members 10-13 comprise roller means 10a-13a, arms 10b-13b, and suspension points 10c-13c for the arms. It will be seen from the figures that each roller means comprises two sets located on the opposite sides of the arm. The first hydraulic lifting means 14-15 comprise hydraulic cylinders 14 and 15 constituted by cylinder members 14a, 15a and piston members 14b, 15b. The first hydraulic lifting means, i.e. cylinders 14, 15, receive pressure from pressure lines 50, 60. In a preferred embodiment, the apparatus com- prises substantially horizontal shafts 18, 19 supported to the frame. The pairs of support members 10-11 and 12-13 adjoin the shafts 18, 19 through the arms 10b-13b ' of the support members at suspension points 10c-13c. In the preferred embodiment, the shafts 18, 19 are dis- posed in the direction of the side portions 2 and 3 of the frame structure 1-3. Thus the shafts 18, 19 adjoin the side portions 2, 3 of the frame. The shafts 18, 19 are parallel. Such a construction is simple, space-con¬ suming and mechanically durable, and enables easy lift- ing of the support members. In the preferred embodiment, the arms 10b, lib of at least one support member pair 10-11 are turnably adapted to adjoin the shafts 18, 19. The first hydr¬ aulic lifting means 14-15 lifting the support member pair 10-11 are thus adapted to turn the arms 10b, lib and hence also the support member pair 10, 11 relative to the shafts 18, 19. These first hydraulic means, i.e. hydraulic cylinders 14, 15, are preferably provided between the arms 10b, lib. The cylinder members 14a, 15a are attached to the shafts 18, 19. The piston means 14b, 15b are attached to the arms 10b, lib. In a preferred embodiment, the second pair of support members is fixedly adjoined to the shafts 18, 19. In such a case, the suspension points 12c, 13c are for instance bolted or welded to the shafts 18, 19. The second hydraulic lifting means 16 comprise parts 16a-16e. Thus in a preferred embodiment the apparatus comprises a guide 16a and a lifting unit 16b hydraulically lifted relative to the guide 16a, the lifting unit 16b being connected to hydraulic pressure generated by the actuator 8. In the figures, these second hydraulic lifting means 16a-16e also comprise a piston 16c located within the guide 16a and a hydraulic pressure chamber 16d. The chamber 16d and piston 16c actually constitute a third cylinder that receives pressure from the actuator, i.e. hydraulic pump 8. Hydraulic pressure is delivered to the chamber 16d by the actuator, i.e. pump 8, through pressure line 16e. The lifting force from the pressure chamber 16d is delivered via piston 16c further through a connecting member 16f to the lifting unit 16b. The figures also show a second guide 17a and a lifting unit 17b lifted in relation thereto. The second lifting unit 17b does not necessarily need a hydraulic lifting arrangement of its own, since the apparatus comprises an intermediary member 20 between the lifting unit 16b, 17b. The arran¬ gement represented by structural parts 16a-16f is an 'in-guide hydraulic arrangement' . Lifting of the second pair of support elements 12-13 has been effected by using in-guide (16a) hydr¬ aulics in such a manner that in a preferred embodiment, the apparatus incorporates dog means 21, 22 between the shafts 18, 19 and the lifting unit 16b, 17b. By means of the above shafts 18, 19 and dog means 21, 22, it has been possible to embody a technically reliable and structurally uncomplicated apparatus oper¬ ating with little power consumption. In a preferred embodiment, the hydraulic lifting arrangement comprises an adjusting means 23 for apply- ing the hydraulic lifting pressure alternatively to both pairs of support elements 10-11 and 12-13 or to only one support element pair 10-11 or 12-13, prefer¬ ably to the support element pair 10-11 in particular. An arrangement wherein the lifting pressure is applied to the support element pair 10-11, in practice to cylinders 14, 15, is needed in performing an inclina¬ tion adjustment, which is necessary when the twin wheels 6, 7 are mounted on the shaft 5, whereby the twin wheels 6, 7 must be brought into alignment with the shaft 5. In inclination adjustment, the alignment of the twin wheels is set to correspond to the align¬ ment of the shaft 5 of the vehicle, thus allowing easy installation of the twin wheels. The adjusting means 23 is shown in Figure 2 only. In a preferred embodiment, the adjusting means 23 is a three-way valve or an equivalent means. The oper¬ ation of the adjusting means 23 is illustrated by Fig¬ ure 2 and reference characters Al, A2, A3 therein, representing the different positions of the adjusting means 23. The adjusting means 23 comprises an inlet 23a from the pump 8, and an outlet 23b to the first hydr¬ aulic lifting means, i.e. cylinders 14, 15. Further¬ more, the adjusting means 23 comprises an outlet 23c to the pressure chamber 16d provided within the guide 16a. In position Al of the adjusting means 23, the hydraulic actuator, i.e. pump 8, pumps pressurized oil through the three-way valve 23 into all three cylinders 14, 15 and 16d. Since a hydraulic pressure is exerted on the cylinder 16d, i.e. pressure chamber, the piston 16c rises the lifting units 16b, 17b, i.e. framework, and by way of the dog means 21, 22 and the shafts 18, 19, also lifts the support members 12, 13 attached to the shafts 18, 19, i.e. the second pair of support mem¬ bers 12, 13. Also the first pair of support members 10- 11 will be lifted, firstly because the cylinders 14, 15, more specifically the cylinder members 14a, 15a, are pressurized, and secondly because they are attached to the shafts 18, 19, which again are turned by the dog means 21, 22, the dog means being lifted on account of the rising of the lifting units 16b, 17b by the action of the piston 16c when the pressure chamber 16d is pressurized. Position Al of the adjusting means 23 is, in a sense, a "floating" position, since in this position each pair of support members is connected to the common hydraulic pressure, and thus each pair of support mem¬ bers 10-11, 12-13 is lifted until it engages the twin wheels. In this way, the support members are accommodated to the position of the twin wheels 6, 7. Hence the support members 10-13, i.e. support members pairs 10-11 and 12-13, support the twin wheels so as to render them in alignment with the direction of the vehicle shaft 5. The above "floating" phase is elucidated by the description of the method of the invention with refer- ence to Figure 3. In the method, the twin wheels are handled with a lifting apparatus comprising two hydr- aulically lifted pairs of support members 10-11 and 12- 13, the shaft 5 of the vehicle being freely supported, for example elevated by means of a jack. In this method, the twin wheels 6, 7 are lifted onto the sup¬ port of the pairs of support members 10-11 and 12-13 of the lifting apparatus. In the method, the hydraulic lifting of the support member pairs 10-11 and 12-13 is performed using a common hydraulic pressure in such a way that upon encounter of one support member pair, e.g. pair 12-13, with the lower surface of a wheel, such as wheel 6, of the twin wheels, the lifting of the pair of support members 12-13 is discontinued self- actuatedly. While the lifting of the pair of support members 12-13 is discontinued and the hydraulic pres¬ sure is further increased by the pump 8, the hydraulic pressure will find an easier route and be directed to lift the other pair of support members 10-11 until that pair of support members 10-11 engages the lower surface of the other wheel 7 of the twin wheels, whereafter the twin wheels are lifted onto support of the pairs of support members by lifting slightly each support member pair as necessary, and consequently the twin wheels no longer rest on the shaft 5. In Figure 3, the inclination of the shaft 5 and the wear of the tyres 6a, 7a is such that tyre 6a at support member pair 12-13 is lower than tyre 7a at support member pair 10-11. Thus in the above example the movement of support member pair 12-13 has stopped as that support member pair 12-13 has engaged the lower surface of the wheel 6. Since support member pair 10-11 is lifted by the same common hydraulic pressure as sup¬ port member pair 12-13, and since support member pair 12-13 is incapable of rising but support member pair 10-11 is capable of rising, the pressure will find an obstruction-free route, i.e. continue lifting the pair of support members 10-11 until the pair of support members 10-11 also engages the lower surface of the twin wheels 6, 7, which gives the situation shown in Figure 3. Position A2 of the adjusting means, e.g. three- way valve 23, is a position in which the pairs of sup¬ port members 10-11 and 12-13 are locked in such a way that neither of them will change its position relative to the other pair. In such a situation, hydraulic pres¬ sure will be delivered into cylinder 16d while in cyl¬ inders 14 and 15 the pressure remains unchanged. As a result, cylinder 16d lifts the second pair of support members 12-13 by way of the piston 16c, lifting units 16b, 17b, dog means 21, 22, and shafts 18, 19. Also the first pair of support members 10-11 will be lifted, since cylinders 14 and 15 are connected with their lower ends to the shafts 18, 19, and since in position A2, the cylinders 14, 15 are locked. Position A2 is needed when the twin wheels 6, 7 to be mounted on the shaft 5 or dismounted from the shaft 5 are lifted to the correct height. In position A2, the twin wheels can be lifted and lowered without altering their inclina- tion. Position A3 is a position in which hydraulic pressure is delivered to the first hydraulic lifting means, i.e. cylinders, 14, 15. The pressure in cylinder 16d remains constant. The pair of support elements 10- 11 to be inclined relative to the shafts 18, 19 can then be lifted by means of the pump 8 and lowered by means of the valve 8b. Position A3 is needed after position A2, since in mounting of the twin wheels 6, 7 on the shaft 5, after lifting of the twin wheels their inclination must be separately adjusted to be in align¬ ment with the inclination of the shaft. The drawings and the appertaining description are only intended to illustrate the idea of the invention. In its details the arrangement in accordance with the invention may vary in many ways within the scope of the inventive idea disclosed in the claims.

Claims: Claims: 1. An apparatus for handling twin wheels of a vehicle, in particular for removing twin wheels (6, 7) from a shaft (5) of the vehicle and for installing them on the shaft (5), the apparatus comprising a frame structure (1-3), two pairs of support members (10-11 and 12-13), and a hydraulic lif ing arrangement com¬ prising at least a hydraulic actuator (8) for lifting the pairs of support members (10-11 and 12-13), c h a r a c t e r i z e d in that the pairs of support members (10-11 and 12-13) are arrayed in two pairs of support members (10-11 and 12-13) that can be lifted separately, that the hydraulic lifting arrangement com- prises first hydraulic lifting means (14, 15) connected to the hydraulic actuator (8) and coupled to lift the first pair of support members (10-11) and second hydr¬ aulic lifting means (16a-16f) coupled to lift the second pair of support members (12-13), and that the first and second hydraulic lifting means (14, 15, 16a- 16f) are connected to a common hydraulic pressure generated by the hydraulic actuator (8). 2. An apparatus as claimed in claim "1, c h a r ¬ a c t e r i z e d in that it comprises substantially horizontal shafts (18, 19) supported to the frame (1- 3), and that the pairs of support members (10-11 and 12-13) are adapted to adjoin the shafts (18, 19) through arms (10b-13b) of the support member pairs. 3. An apparatus as claimed in claim 2, c h a r - a c t e r i z e d in that the arms (10b, lib) of at least one support member pair (10-11) are turnably adapted to adjoin the shafts (18, 19) and that the first hydraulic lifting means (14, 15) lifting the sup¬ port member pair (10-11) are adapted to turn the sup- port member pair (10-11) relative to the shafts (18, 19). 4. An apparatus as claimed in claim 2 or 3, c h a r a c t e r i z e d in that the second pair of support members (12-13) is fixedly adjoined to the shafts (18, 19), that the apparatus comprises a guide construction (16a, 17a) and a lifting unit (16b, 17b) hydraulically lifted relative to the guide con¬ struction, and a pressure cylinder (16d) connected to hydraulic pressure generated by the hydraulic actuator (8), the guide (16a), lifting unit (16b) and pressure cylinder (16d) forming second hydraulic lifting means (16a-16e), and that the apparatus incorporates dog means (21, 22) between the shafts (18, 19) and the lifting unit (16b, 17b). 5. An apparatus as claimed in claim 1, c h a r ¬ a c t e r i z e d in that the hydraulic lifting arran¬ gement comprises an adjusting means (23) for applying the hydraulic lifting pressure alternatively to both pairs of support elements (10-11 and 12-13) or to only one support element pair (10-11 or 12-13). 6. An apparatus as claimed in claim 5, c h a r ¬ a c t e r i z e d in that the adjusting means (23) is a three-way valve or an equivalent means. 7. An apparatus as claimed in claim 2 or 3, c h a r a c t e r i z e d in that the first hydraulic lifting means (14, 15) comprise hydraulic cylinders (14a, 14b, 15a, 15b), and that the hydraulic cylinders (14a, 14b, 15a, 15b) are provided between the shafts (18, 19) and the arms (lOb-llb) of the support member pair (10-11). 8. An apparatus as claimed in claim 1, c h a r ¬ a c t e r i z e d in that the hydraulic actuator (8) is a hydraulic pump, and that the actuator, preferably a hydraulic pump (8), comprises a pressure relief means (8b), preferably a valve. 9. An apparatus as claimed in claim 2, c h a r ¬ a c t e r i z e d in that the shafts (18, 19) are dis- posed in the direction of side portions (2, 3) of the frame structure (1-3). 10. A method for handling twin wheels of a vehicle, in particular for removing twin wheels (6, 7) from a shaft (5) of the vehicle and for installing them on the shaft (5), in which method the twin wheels (6, 7) are handled with a lifting apparatus comprising two pairs of hydraulically lifted support members (10-11 and 12-13) while the shaft of the vehicle is freely supported, and in which method the twin wheels (6, 7) are lifted onto the support of the pairs of support members (10-11 and 12-13) of the lifting apparatus, c h a r a c t e r i z e d in that in the method the hydraulic lifting of the pairs of support members (lu¬ ll and 12-13) is performed by a common hydraulic pres- sure in such a way that when the first pair of support members (10-11 or 12-13) engages the lower surface of the first wheel (6 or 7) of the twin wheels (6, 7), the lifting of the pair of support members is discontinued self-actuatedly and the hydraulic pressure is directed to lift the second pair of support members (12-13 or 10-11) until that pair of support members engages the lower surface of the second wheel (7 or 6) of the twin wheels, whereafter the twin wheels (6, 7) are lifted onto the support of the pairs of support members (10-11 and 12-13) by at least slightly lifting each support member pair (10-11 and 12-13). 11. A method as claimed in claim 10, c h a r ¬ a c t e r i z e d in that mounting the twin wheels (6, 7) on the shaft is realized by performing a hydraulic inclination adjustment wherein the alignment of the twin wheel (6, 7) is set to correspond to the alignment of the shaft (5) of the vehicle by hydraulic lifting or lowering of one pair of support members (10-11).

Inventors: HUUSKO OLAVI, LAAKSONEN JUKKA, LAAKSONEN REIJO, HUUSKO, OLAVI, LAAKSONEN, JUKKA, LAAKSONEN, REIJO
Applicants: AUTO JURE OY, HUUSKO OLAVI, LAAKSONEN JUKKA, LAAKSONEN REIJO, AUTO-JURE OY, HUUSKO, OLAVI, LAAKSONEN, JUKKA, LAAKSONEN, REIJO
Application year: 1995
Main classification: B60B29
IPC codes: B60B29, B62B3