Abstract:
A method for slowing transfer of a heavy work machine on a sloping base using a transportation device equipped with wheels, the work machine including a body, a crawler chassis fitted beneath the
       body, a set of booms having at least one operating cylinder, a first end and a second end, said set of booms being pivoted at the first end to the work machine and a selected auxiliary device is pivoted at the second end, and a brake surface connected to the auxiliary device, in which method includes the steps of   transferring the work machine by supporting the work machine on the crawler chassis at least partly on top of the transportation device,   towing the work machine using a transfer vehicle with the aid of the transportation device,   using said operating cylinder of the set of booms to press the brake surface against the sloping base to create friction to slow transfer speed of the transportation device on the sloping base, and   adjusting pressing of the brake surface taking place through the auxiliary device using the operating cylinder or one set of booms. An arrangement in connection with a heavy work machine for transferring the work machine on a sloping base is also described.

Description:
[0001]    This application claims benefit of priority from International Patent Application No: PCT/FI2015/050859 filed Dec. 7, 2015, which claims benefit of Finland Patent Application No. 20146074, both of which are incorporated by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a method for slowing transfer of a heavy work machine on a sloping base, in which the work machine includes a body, a crawler chassis fitted beneath the body, and a sat of booms pivoted at its one end to the work machine, at the other end of which is a selected auxiliary device, and a transportation device is equipped with wheels, in which method the work machine is transferred by supporting the work machine on the crawler chassis at least partly on top of the transportation device, and towing the work machine using the transfer vehicle with the aid of the transportation device and using friction to slow the transfer speed of the transportation device on the sloping base. The invention also relates to an arrangement for transferring a heavy work machine on a sloping base. 
       BACKGROUND OF THE INVENTION 
       [0003]    The transfer of heavy excavators equipped with crawler tracks, for example, in mines and quarries, is problematic. It is sought to avoid long transfers of excavators with suspensions equipped with crawler tracks, as long transfers are slow and wear the suspensions unnecessarily, shortening their service life. 
         [0004]    Patent publication FI 101779 B is known from the prior art disclosing a transportation device for moving an excavator from one place to another on wheels. The excavator is driven on its crawler tracks partly on top of the wheels and the crawler traces of the excavator are finally raised off the ground with the aid of a set of booms supported on the load space of a transfer vehicle, for example, a dump truck, with the aid of the bucket of the excavator. In this way, the excavator can be moved rapidly and without stressing the tracks from one work site to another. 
         [0005]    However, a problem in such, a solution is the great mass of an excavator when moving it on a sloping base. When then moving an excavator using the transportation device according to the aforementioned patent, the towing transfer vehicle must be responsible for producing power both to transfer and to brake the excavator. When correctly dimensioned, the power of the transfer vehicle will be sufficient for the transfer; but braking effect often becomes a problem. At a mine, an excavator or other work machine must often be transferred on a sloping base, i.e. downhill, when a great deal of braking effect will be required. The brakes of the transfer vehicle will then be insufficient to produce the necessary braking power, or at least will operate at the extreme limit of their capacity. 
         [0006]    In addition, a problem in such transfers is the slipperiness of the sloping base, for example, in winter or in rain, when an excavator or work machine with a great mass can push the transfer vehicle downhill in front of it, causing a great hazard. The base material too can be slippery. The safety philosophy of the sector is generally based on the idea that the speed, of transfer of all moving work machines must be such that they can be stopped if necessary. In addition to excavators, the problem can also appear in connection with other heavy work machines equipped with a work boom. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention is intended to create a method that is safer and simpler than methods of the prior art for transferring a heavy work machine, by means of which the braking effect can be increased. This intention can be achieved by means of a method for slowing transfer of a heavy work machine on a sloping base using a transportation device equipped with wheels, the work machine comprising a body, a crawler chassis fitted beneath the body, a set of booms having at least one operating cylinder, a first end and a second end, said set of booms being pivoted at the first end to the work machine and a selected auxiliary device having a brake surface is pivoted at the second end, in which method transferring the work machine by supporting the work machine on the crawler chassis at least partly on top of the transportation device, towing the work machine using a transfer vehicle with the aid of the transportation device, using said operating cylinder of the set of booms to press said brake surface of the auxiliary device attached to the second end of the set of booms against the sloping base to create friction to slow transfer speed of the transportation device on the sloping base, adjusting pressing of the brake surface taking place through the auxiliary device using the operating cylinder of the set of booms. 
         [0008]    The invention is also intended to create a safer and simpler arrangement than arrangements of the prior art in connection with a heavy work machine, by means of which the braking effect can be increased. This intention can foe achieved by means of an arrangement for transferring a heavy work machine on a sloping base, in which arrangement the heavy work machine comprising a body, a crawler chassis fitted under the body and a set of booms having at least one operating cylinder, a first end and a second end, said set of booms being pivoted at the first end to the work machine, and the arrangement includes a transportation device equipped with wheels, on top of which transportation device the work machine is arranged to be at least partly supported for duration of transfer, a transfer vehicle for towing the work machine during the transfer, the work machine being at least partly supported on top of the transportation device, a selected auxiliary device at the second end of said set of booms at a distance from the body, said auxiliary device having a brake surface for retarding the transfer speed of the work machine with the aid of friction arranged to be pressed against the sloping base by using said operating cylinder of the set or booms with the aid of the auxiliary device to brake the transfer speed of the work machine during the transfer with the aid of friction an operating device for using the operating cylinder to press the brake surface of the auxiliary device against the sloping base. 
         [0009]    The idea of the method according to the invention is to continuously brake the transfer of a work machine equipped with a set of booms on a sloping base while it is being transferred, making separate brakes unnecessary. This also creates a safer way to transfer a heavy work machine equipped with a set of booms, as, if a fault develops in the transfer vehicle, the work machine equipped with a set of booms will stop itself, thanks to the continuous braking. More specifically, the intention of the method according to the invention can be achieved with the aid of a method for slowing the transfer of a heavy work machine on a sloping base, in which the work machine includes a body, a crawler chassis fitted under the body, and a set of booms, which is pivoted at its one end to the work machine and at the other end of which is a selected auxiliary device. The transportation device is equipped with wheels. In the method, the work machine is moved by supporting the work machine on its crawler chassis at least partly on fop of the transportation device, towing the work machine using the transfer vehicle with the aid of the transportation device, using the auxiliary device to press a brake surface against the base to retard the transfer speed, and to use the set of booms to adjust the pressing of the brake surface created through the auxiliary device. In this way, the transfer speed, of the transportation device is slowed on a sloping base by using friction. In the method according to the invention, the braking effect is created by means of friction between the braking surface and the base, exploiting the mass of the heavy work machine by using the operating cylinder of the set of booms to press the brake surface of the auxiliary device against the sloping base. During braking, the pressing on the brake surface, which is supported on the base, is increased with the aid of the set of booms of the work machine, by means of the auxiliary device. Using the method according to the invention, the importance of the braking effect of the transfer vehicle is reduced and by using a transfer vehicle with sufficient towing power very large work machines equipped with sets of booms can be transferred downhill too in a controlled manner and safely. 
         [0010]    The set of booms preferably includes one or more sequentially pivoted booms. With the aid of the set of booms, the bucket preferably acting as the auxiliary device can be rotated to several different attitudes, depending on the operating situation. 
         [0011]    According to one embodiment, in the method a pair of transfer wheels fitted to only one end of the work machine is used as the transportation device. The weight can then be distributed in a suitable ratio between the pair of transfer wheels and the brake surface, using the set of booms to create the desired braking effect. 
         [0012]    In the method, the work machine is preferably towed by the transfer vehicle by means of a rope. A rope will have sufficient strength for the purpose, but be considerably lighter than a steel cable of similar strength. In addition, if it breaks, a rope will, not cause a danger corresponding to a steel cable, the internal tension of which causes a sharp movement in the ends of the cable in a breaking situation. 
         [0013]    The rope used is preferably as marine-industry rope, for example, a rope of polyethylene with a high molecular weight, sold under the Dyneema trademark, which is processed by stretching to achieve a high molecular orientation and crystallinity of the molecules. The molecular orientation of polyethylene manufactured in this way is more than 95% and the crystallinity of the molecules more than 85%. 
         [0014]    The mass of the work machine can be more than 50 tn, preferably more than 100 tn. Longer transfers of such work machines are particularly slow and wearing on the crawler chassis. When transferring such machines on a sloping base, the braking effect of the transfer vehicle often becomes a limiting factor to the transfer. 
         [0015]    The brake surface is preferably arranged in connection with the set of booms. The pressing of the brake surface against the ground can be easily adjusted with the aid of the set of booms. 
         [0016]    According to one embodiment, the transfer speed is slowed by supporting the brake surface continuously on the base, so that the brake surface is towed continuously with the aid of the transfer vehicle. In other words, the brake surface or transfer vehicle incorporating a brake surface attached to the work machine by means of an auxiliary device, is towed continuously, i.e. the work machine being transferred requires the towing power of the transfer vehicle downhill too, or else the work machine will stop automatically. 
         [0017]    The towing power can be directed through the set of booms to the following work machine. The work machine connected to the brake surface with the aid of the set of booms will then steadily follow the towing transfer vehicle. 
         [0018]    The work machine equipped with a set of booms is advantageously an excavator and the brake surface is fitted to the excavator in connection with its bucket. 
         [0019]    The braking effect is preferably adjusted by altering the attitude of the brake surface. Thus, the braking effect can be simply adjusted from the work machine to suit each situation. By adjusting the braking effect, savings can be achieved in the fuel consumption of the transfer vehicle. 
         [0020]    According to one embodiment, the braking effect can be adjusted by adjusting the distance between the brake surface and the work machine. Such an adjustment, is limited, however, by the limited power produced by the set of booms, which prevents the bucket from being brought very close to the work machine. 
         [0021]    According to a second embodiment, the operator adjusts the braking effect manually from the work machine. To implement the method, all that is required, in addition to the systems available in transfers of the prior art, is a brake surface fitted in connection with the set of booms of the work machine. The operator can adjust the braking effect by rotating the bucket, for example on the basis of feedback given by the driver of the transfer vehicle, or by visually estimating the braking effect. 
         [0022]    According to a third embodiment, the braking effect is measured actively and the braking effect is adjusted automatically on the basis of the measurement data. The excavator can then be braked during the transfer without active operation by the excavator driver. 
         [0023]    The braking effect is preferably maximal when starting to move and the braking effect is reduced once the excavator is moving by altering the attitude of the bucket. Reducing the braking effect during transfer saves fuel in the transfer while the maximal braking effect when starting the transfer in turn ensures sufficient transfer power in the transfer vehicle. 
         [0024]    The towing power between the transfer vehicle and the work machine is preferably measured with the aid of a sensor. The measurement result can be displayed to the drivers of both the transfer vehicle and the work machine, who can adjust the towing power and braking on the basis of this information. 
         [0025]    The objective of the arrangement according to the invention can, in turn, be achieved by means of am arrangement for transferring a heavy work machine on a sloping base, which heavy work machine includes a body, a crawler chassis fitted under the body, and a set of booms pivoted at its one end to the work machine, and at the other end of which is a selected auxiliary device. The arrangement includes a transportation device equipped with wheels, on top of which the work machine is arranged to be at least partly supported during the transfer, a transfer vehicle for towing the work machine during the transfer when the work machine is at least partly supported on top of the transportation device, and brake means for slowing the transfer speed of the work machine with the aid of friction. The brake means is a brake surface at a distance from the body, arranged to be pressed against the base to brake, with the aid of friction, the transfer speed of the work machine during the transfer. With the aid of the brake surface, the mass of the work machine can be exploited to create sufficiently high friction between the brake surface and the base to create sufficient retardation under all circumstances. The construction is economical to implement and operate. 
         [0026]    The heavy work machine is preferably an excavator, which includes a set of booms with a bucket pivoted to it. Excavators can be very heavy, which aggravates the problem of braking on a sloping base. 
         [0027]    According to one embodiment, the brake surface is a separate drag plate, which is attached to the bucket. Thus, the bucket can be a bucket according to the prior art, which can be retrofitted with the necessary brake surface. In addition, the separate piece can be easily changed when the brake surface wears in use. 
         [0028]    According to a second embodiment, the brake surface is a brake area formed in the bucket. The brake surface is then an integrated part of the bucket and thus extremely strong. In addition, a brake surface belonging to the bucket is a simpler totality to manufacture than a brake surface separately attached to the bucket. 
         [0029]    The brake surface preferably includes at least two brake areas with different coefficients of friction. Thus, by altering the attitude of the work machine&#39;s brake surface, the coefficient of friction between the brake surface and the ground can be altered, simultaneously altering the braking effect. 
         [0030]    According to one embodiment, each brake area is at an angle of 5-25°, preferably 10-15° to the adjacent brake area. Thus, when the excavator&#39;s bucket is rotated around the pivot point between it and the set of booms, the bucket&#39;s brake surface changes between brake areas of a different size and coefficient of friction. Thus, the braking effect can be easily adjusted for different surface formations and conditions of the base. 
         [0031]    In the arrangement, a tope is preferably used to tow the work machine, which rope is a rope known from marine industry, described in the method. 
         [0032]    The arrangement can include a towing rope arranged between the transfer vehicle and the excavator for towing the excavator and an anchor point formed in the said bucket for attaching the towing rope or cable to the excavator. The anchor point permits the excavator to be towed from near to the brake surface. 
         [0033]    In the arrangement, the jaw-crashing surfaces of a jaw crusher are preferably used as the brake surface. These are pieces of an extremely durable material, which can be adapted almost directly as brake surfaces. Alternatively, a brake surface especially suitable for the purpose can be manufactured from a corresponding material. 
         [0034]    The arrangement according to the invention is preferably arranged to be used with the aid of the method according to the invention described above. 
         [0035]    According to a third embodiment, the arrangement includes a separate transfer trailer, which is arranged to be towed by a transfer vehicle, and which includes a arm for attaching the transfer trailer to the transfer vehicle, a second arm supported on the first arm with the aid of a transverse pivot, wheels that are supported with the aid of an axle on the second arm, a brake surface for braking the transfer of the work machine, fitted to the undersurface belonging to the second arm, a support plane for supporting the bucket on the transfer trailer, and locking means arranged in connection with the support plane for locking the bucket to the transfer trailer. With the aid of such an arrangement, the brake surface can be simply kept off the base during transfers taking place on a level base, but again use the set of booms to press the brake surface onto the base when braking on a hill. 
         [0036]    The second arm can form the support plane. Such an implementation is particularly suitable for transfer trailers, which are towed by a heavy transfer vehicle, in which the towing adhesion is sufficient. 
         [0037]    Alternatively, the arm can form the support plane. Such an implementation is particularly suitable for transfer trailers that are towed by lighter transfer vehicles, in which case, by pressing the arm by the set of booms of the work machine, additional, mass is transferred to the transfer vehicle, in order to improve towing adhesion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    In the following, the invention is described in detail with reference to the accompanying drawings showing some embodiments of the invention, in which 
           [0039]      FIG. 1 a    shows an overall side view of the arrangement according to the invention, in which an excavator is towed by a transfer vehicle during transfer, 
           [0040]      FIG. 1 b    shows an overall side view of the arrangement according to the invention, in which an excavator is towed by a transfer vehicle during transfer, in an opposite sequence to that in  FIG. 1   a,    
           [0041]      FIG. 1 c    shows an overall side view of an arrangement according to a second embodiment, in which an excavator is towed by a transfer vehicle during transfer, 
           [0042]      FIG. 2  shows a side view of the bucket of the excavator of the arrangement according to the invention, when the brake surface is arranged in a separate drag plate, 
           [0043]      FIG. 3  shows an axonometric view at an angle from in front of the bucket of the excavator according to the invention, when the brake surface is arranged in a separate drag plate, 
           [0044]      FIG. 4  shows an axonometric view at an angle from the rear of the bucket of the excavator according to the invention, when the brake surface is arranged in a separate drag plate, 
           [0045]      FIG. 5  shows an axonometric view of the bucket of the arrangement according to the embodiment of  FIG. 1 c    in the open position when attaching the brake means, 
           [0046]      FIG. 6  shows an axonometric view of the bucket of the arrangement according to the embodiment of  FIG. 1 c    in the closed position, when the brake means have been attached, 
           [0047]      FIG. 7  shows an axonometric view of the brake shoe of the arrangement according to the embodiment of  FIG. 1   c,    
           [0048]      FIGS. 8 a  and 8 b    show a side view of a third embodiment of the arrangement according to the invention, seen when using two different types of bucket, 
           [0049]      FIGS. 9 a  and 9 b    show a side view of a third embodiment of the arrangement according to the invention, seen when using two different types of bucket when the bucket is on the second possible support plane, 
           [0050]      FIGS. 10 a  and 10 b    show an axonometric view seen at an angle from the rear when using two different types of bucket, 
           [0051]      FIGS. 11 a  and 11 b    show a side view the operation of the brake surface of a third embodiment according to the invention, 
           [0052]      FIG. 12  shows a partial side cross-section of the third embodiment of  FIG. 11   a.    
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0053]      FIG. 1 a    shows a side view of the construction of the arrangement according to the invention. According to  FIG. 1   a,  the arrangement includes a heavy work machine  10  preferably equipped with a set of booms  20 , which is transported, with the aid of a transportation device  12  preferably equipped with wheels  15 , by towing the work machine  10 , for example, by means of a rope  33 , with a transfer vehicle  14 . The set of booms  20  is pivoted at its one end  17  to the body  13  belonging to the work machine  10 , with the aid of a pivot  21 . The set of booms  20  also includes at least one operating cylinder  29 . Instead of the rope, a cable can also be used, but a rope is a lighter and safer implementation.  FIGS. 1 a   - 4  show a preferred embodiment of the invention, in which the heavy work machine  10  equipped with a set of booms  20  is an excavator  10 ′, which includes an auxiliary device  55 , i.e. in this case a bucket  18 , pivoted to the set of booms  20 . Instead of a bucket, the auxiliary device can also be some other auxiliary device at the end of the set of booms, which is used in a heavy work machine. The heavy work machine equipped with a set of booms can also be, for example, a bulldozer, a drilling unit, or some similar work machine, in which there is preferably a crawler chassis  11 . In addition, the arrangement includes brake means  30 . The work machine  10  can be towed toy a transfer vehicle with the brake means  30  in front, according to  FIG. 1   a,  in which case the towing force is advantageously directed through the set of booms  20  to the following work machine  10 . Alternatively, the work machine  10  can also be towed according to  FIG. 1   b,  in which case the towing force is directed directly to the work machine  10 , which is partly on top of a transportation device  12 . In this connection, the term set of working booms can also be used for the set of booms. 
         [0054]      FIG. 1 c    shows a second embodiment of the arrangement, is which the work machine  10  is an excavator equipped with a dipper shovel  18 ′. When using a dipper shovel  18 ′, the brake means  30  differ slightly in construction from the embodiment of  FIGS. 1 a    and  1   b,  mainly due to the operating attitude of the dipper shovel  18 ′. The dipper shovel  18 ′ differs in construction from the bucket  18  of the embodiment of  FIGS. 1 a  and 1 b    in that the dipper shovel  18 ′ consists of a body part  50  and a jaw part  52  pivoted to it  52 . The dipper shovel is loaded with the jaw part  52  closed on the body part  50  and is discharged, in turn, by opening the jaw part  52  by rotating it around the pivot, according to  FIGS. 5 and 6 . 
         [0055]    Differing from the embodiments of  FIGS. 1 a   - 1   c,  the transportation device can also be, for example, a transportation device equipped with sliding surfaces. Similarly, the work machine to be transferred can also be a work machine that is implemented without a set of booms. In that case, the brake surface is attached to the chassis of the work machine with tee aid of a separate pivot mechanism and adjustment of the braking effect still takes place by rotating the brake surface. Preferably, the transportation device is, however, for example, the Sleipner set of wheels made generally known by the applicant. 
         [0056]    According to the invention, the excavator  10 ′ of  FIG. 1 a    is supported on the transportation device  12  in such a way that the excavator&#39;s  10 ′ crawler chassis  11  can be raised off the base  16 , i.e. preferably off the surface of the ground or road. The excavator&#39;s  10 ′ crawler chassis  11  is raised off the base  16  by using the excavator&#39;s  10 ′ set of booms  20 , which is used to press the ground with the aid of a bucket  18  suspended from the set of booms  20 , until the crawler chassis  11  rises off the base  16 . The set of booms  20  is pressed by using the operating cylinder  29  of the set of booms  20  which is controlled with a operating device  27 , for example a joystick, included in the arrangement. In the arrangement and method according to the invention, the transportation device  12  can be a pair of transfer wheels like that shown in  FIG. 1 a    or, for example, a traditional transportation carriage, by means of which the excavator&#39;s crawler chassis is raised off the base. In the method according to the invention, the weight of the excavator  10 ′ is directed to the base  16  through the transportation device  12  and the brake means  30  connected to the bucket  18  of the excavator  10 ′. 
         [0057]    In the method according to the invention, the transfer downhill of the excavator  10 ′ takes place preferably by towing the excavator  10 ′ on the transportation device  12  with the transfer vehicle  14 , when it is supported, continuously on the base  16  with the aid of the brake means  30  connected to the work machine  10 . In the embodiment of  FIGS. 1 a   - 4 , the brake means  30  are attached to the excavator&#39;s  10 ′ bucket  18 . During the transfer, the movement of the excavator  10 ′ is retarded by continuous dragging on the ground by means or the brake surface. The transfer preferably requires continuous pulling by the transfer vehicle, as the force continuously directed advantageously to the ground through the brake surface causes such a great resistance that the excavator will stop, even when going downhill, without continuous towing. Using the method according to the invention, the decisive criterion in terms of the transfer is the towing power of the transfer vehicle, and not its braking power, contrary to the methods according to the prior art. Further, preferably by altering the attitude of the brake surface, i.e. for example, the attitude of the bucket  18  of the excavator  10 ′, the retardation can be adjusted as required. Retardation can also be adjusted by altering the distance of the brake surface from the excavator, when the distribution of the weight of the excavator between the transportation device and the brake surface will change. Depending on the slipperiness of the base, the friction between the base and the brake surface can be altered by altering the attitude of the brake surface, so that it will be sufficient to stop the work machine. 
         [0058]    In the method according to the invention, the brake surface belonging to the brake means can be formed directly in the excavator&#39;s bucket, in a separate drag plate that is attached to the excavator&#39;s bucket, or in a separate transfer carriage.  FIGS. 1 a   - 4  show an embodiment, in which the brake surface  22  of the brake means  30  is formed in a drag plate  24 .  FIG. 2  shows a side view of the drag plate  24  in greater detail. The drag plate  24  can be a plate-like structure formed by welding metal pieces, which has its own frame  25  with the aid of which the drag plate  24  is attached to the bottom  19  of the excavator&#39;s bucket  18  ( FIG. 4 ) for the duration of the transfer of the excavator. The attachment of the drag plate  24  to the bucket  18  can take place preferably with the aid of separate gripping plates  32 , which form a shape-closing joint with the bucket  18 . In other words, the gripping plates  32  can be plates parallel to the height direction of the bucket  18 , in each of which a slot  44  is formed that is essentially parallel to the bottom plate  13  of the bucket  18 , in accordance with  FIG. 3 . The part of the bucket  18  on the opposite side of the slot  44  relative to the brake surface  22  forms an gripping claw  46  for the drag plate  24 . The gripping plates  32  are preferably situated at a distance from each other, so that they are located between the bucket&#39;s  18  claws  38 . The bucket&#39;s  18  bottom plate  19  can be pushed into the slot  44  in the opposite direction to the direction of movement of the transfer vehicle. When the transfer of the excavator starts, the gripping plates  32  transmit the forwards moving force of the transfer vehicle to the excavator&#39;s bucket and simultaneously lock the excavator&#39;s bucket vertically to the drag plate  24 . In addition, the bucket&#39;s  18  bottom plate  19  can include side supports  40  according to  FIGS. 2 and 4 , which prevent the drag plate  24  from moving transversely. 
         [0059]    According to  FIG. 2 , the brake surface  12  can be a brake area  28  formed in the drag plate  24 . Brake areas  28  with at least two different coefficients of friction can be incorporated in the brake area  28 . Alternatively, the brake area can be formed directly in the bottom plate of the bucket. Having brake areas with different coefficients of friction seeks to obtain different braking effects using the same brake surface. The brake area with the smallest coefficient of friction can be used, for example, on rough gravel roads with a good grip, or similar bases. The second brake area with a higher coefficient of friction can be used, for example, on a wet road or a sandy-like base. The brake area with a third, even higher coefficient of friction can, in turn, be used, for example, on ice. In the brake surface, there are preferably at least two brake areas with different coefficients of friction, irrespective of whether the brake surface is formed directly in the bottom of the excavator&#39;s bucket or in a separate drag plate. The brake areas can also have surface areas that differ relative to each other, so that the broking effect can be altered by altering the brake surface, for example, from a smaller to a larger brake area. In the case of differing surface areas, the different brake areas can also have the same coefficient of friction, as the difference in braking effect is created by the difference in the surface areas of the brake areas. 
         [0060]    According to  FIGS. 2 and 4 , each brake area  28  can be at an angle of 5-25°, preferably 10-15° relative to the adjacent brake area  28 . Thus, the coefficient of friction of the brake surface  22  can be altered by rotating the bucket  18  around the pivot point between it and the set of booms, so that the part of the brake surface  22  in contact with the base changes from one brake area  28  to the other. According to  FIG. 4 , the brake area  28  can include brake claws  34 , by means of which braking effect is obtained, in addition to the brake area  28  forming the brake surface  22 . The brake claws are particularly useful in retarding a transfer on, for example, ice and snow.  FIG. 4  also shows that the brake areas  28  of the brake surface  22  are situated between shoulders  36 . The shoulders  36  lock the advantageously changeable brake areas  28  of the brake surface  22  to the structure of the frame  25  of the drag plate  24 . 
         [0061]      FIGS. 5 and 6  show the attachment of the brake means  30  of the arrangement according to the second embodiment of  FIG. 1 c    to a dipper shovel  18 ′. The attachment preferably takes place in such a way that the jaw part  52  of the dipper shovel  18 ′ is rotated around a pivot in such a way that the dipper shovel  18 ′ opens and the drag plate formed in the drag plate  24  can be placed between the jaw part  52  and the body part  50 . Preferably in this embodiment too the drag plate  24  includes gripping claws  46  and supports  40 ′, with the aid of which the brake surface  22  is locked to the bottom of the dipper shovel  18 ′, when, according to  FIG. 6  the jaw part  52  is closed onto the body part  50 . The gripping claws  46  and supports  40 ′ can be seen more clearly in  FIG. 7 , in which a draw plate  24  according to a second embodiment is shown when detached. 
         [0062]      FIGS. 8 a   - 12  show a third embodiment of the arrangement according to the invention, in which the brake means  30  are fitted in connection with a separate transfer trailer  60  equipped with wheels  54 . The transfer trailer  60  is preferably a transportation means attached, in such a way that it can be towed, to the transfer vehicle  14  with the aid of an arm  64 , i.e. a curved gooseneck, which transportation means includes a brake surface  22  located on a second arm  58  of the other side of the transfer trailer relative to the wheels  54 . The second arm  58  and the arm  64  are preferably connected to each other with the aid of a transverse pivot  86 , in accordance with  FIG. 12 , which pivot  66  is situated in front of the axle of the wheels  54  attached to the second arm  58 . In this case, in front refers to the arm&#39;s  64  side of the axle of the wheels  54 . In this way, according to the invention, the brake surface  22  is weighted with the aid of the set of booms  20  of the work machine and braking is adjusted preferably by rotating the bucket  18  connected to the set of booms  20 , which is locked to the second arm  58 . Rotation of the bucket  18  rotates the second arm  58  around the axle of the wheels  54 , so that the brake surface  22  comes into contact with the base  16 . The transfer trailer also preferably includes locking means, with the aid of which the bucket is locked to the transfer trailer for the duration of the transfer. The locking means can be similar to those described in connection with previous embodiments. 
         [0063]    In the transfer trailer there can be two separate support planes  62 , according to  FIGS. 8 a   - 10   b,  on which the bucket  18  can be attached to the transfer trailer  60 . The support plane  62 , seen in  FIGS. 8 a    and  8   b,  as well as in  10   a  and  10   b,  is between the wheels  54  of the transfer trailer  60  while in  FIGS. 9 a  and 9 b    the support plans  62  is half-way along the arm  64 . The attachment point used can vary according to the transfer vehicle being used. If the transfer vehicle  14  is of light construction, the friction between the wheels of the transfer vehicle  14  and the base  16  may be insufficient for towing a heavy work machine  10 , in which case the support plane  62  according to  FIGS. 9 a  and 9 b    can be used to attach the bucket  18  to the transfer trailer  60 . The arm  64  can then foe pressed with the aid of the set of booms  20  in order to provide additional weight for the wheels of the transfer vehicle and in that way increase adhesion. Thick arrows pointing downwards from the support plane  62  are used in FIG.  9   a  to show the different points that can be pressed according to whether it is wished to increase or reduce the braking effect. By increasing pressure on the bucket  18 , with the aid of the set of booms  20 , at the location of the arrow on. the side near to the transfer vehicle  14 , the loading can be increased on the transfer vehicle  14  and braking can be reduced, while, by increasing pressure at the point on the side nearest the work machine  10  by pressing the bucket  18  with the aid of the set of booms  20 , loading can be increased on the brake surface  22  and the loading on the transfer vehicle  14  can be reduced. 
         [0064]    Alternatively, if the transfer vehicle  14  is heavy and there is no problem with adhesion, the point shown in  FIGS. 8   a,    8   b,    10   a,  and  10   b  can be used, to attach the bucket  18 . According to the figures, the auxiliary device used in the work machine can be either a dipper shovel, or a back hoe, or similar. 
         [0065]    According to one embodiment, the brake surface can be brought into contact with the base by using springing in the suspension of the wheels axle, which with a small pressure from the set of booms of the work machine keeps the brake stir face off the base, but, if the pressure is increased, permits the brake surface to contact the base. Such an implementation is especially suitable for the embodiment according to  FIGS. 9 a    and  9   b.    
         [0066]    In the method according to the invention, the retardation of the transfer speed of the excavator is preferably adjusted on the basis of the towing force between the transfer vehicle and the excavator. The starting point for the adjustment can be regarded as being that, when the towing force is zero, the maximum braking effect is caused by the brake surface connected to the bucket of the excavator. Thus it can be ensured that the retardation of the excavator is always powerful when required. As the towing force increases, the braking effect can be reduced by rotating the brake surface in such a way that a change occurs to the brake surface&#39;s brake area with a smaller coefficient of friction. The magnitude of the towing force can be estimated visually, or on the basis of a separate measurement. On the basis of visual estimation or a measurement result, the excavator operator can rotate the bucket of the excavator to achieve the desired braking effect. Alternatively, a separate radio-control unit can be installed in the excavator, with the aid of which the braking power of the excavator can be adjusted by remote control from the transfer vehicle. 
         [0067]    The arrangement according to the invention can also include, in addition to a sensor, a control device, which, on the basis of a preset control variable automatically adjusts the set of booms of the work machine being transferred, for example, an excavator, to control the braking effect. Braking can then take place entirely automatically. The control device  27  can also be manually operated and located in the excavator  10 ′ as in  FIG. 1   a,  the control device being for example a joystick for manual use. 
         [0068]    In the method according to the invention, a set of transfer wheels like that disclosed in, for example, patent publication FI 101779 B or application publication WO 2013/124543 A1 can be used. The method, can be used, for example, to transfer a 250-tn excavator, in which about 30%, i.e. 75 tn of the excavator&#39;s mass is supported on the base by means of the bucket. The compressive force caused by the excavator  10 ′ going downhill is then 22 tn. If the coefficient of friction between the brake surface and the base is 1, the required towing force will be a maximum of about 53 tn. For example, the maximum towing force of a Caterpillar CAT785D haul truck is 85 tn. The towing-force requirement is influenced by the surface area of the brake surface, the hardness of the base, the moisture content of the base, loose material on the base, and the attitude of the bucket. 
         [0069]    The brake areas of the brake surface can be manufactured from a material suitable for the purpose, for example, wear-resistant steel, the hardness of which is more than 400 (HBW). Crushing-jaw surfaces known from jaw crushers, such as, for example, Metso&#39;s jaw-crusher blade surfaces known under the product name Nordberg C-series, which is made to withstand high stresses and is thus suitable for the purpose, can advantageously be used as the brake surfaces. Various kinds of patterning can also be formed in the surfaces of the brake areas, in order to vary the coefficient of friction. 
         [0070]    The method according to the invention is preferably used when transferring a heavy work machine on a sloping base, for example downhill, but the method can also be used on a level base. The dragging braking of the brake surface on the base can also be used for levelling or ploughing the surfaces of she base, for example, a road.