Abstract:
A driveline for mobile vehicles comprising one multi-disc brake ( 14 ) which non-rotatably connects a rotatable part of a planetary transmission ( 12 ) with the housing ( 4 ) wherein the actuating device of the multi-disc brake has one piston ( 18 ) which has one automatic piston-resetting device ( 21 ), and clamping elements ( 22 ) are situated in holes ( 40 ) of the piston ( 18 ).

Description:
FIELD OF THE INVENTION 
   The invention concerns drivelines for mobile vehicles. 
   BACKGROUND OF THE INVENTION 
   According to the preamble, drivelines are especially used for mobile vehicles, for example, construction machinery such as loaders, in order to drive or brake the wheels of the vehicle. It is of particular importance that it is possible to operate the brake existing in said drivelines with a steady function. 
   U.S. Pat. No. 6,090,006 discloses a driveline for mobile vehicles having a planetary transmission in which the rotating inner discs of a multi-disc brake are located on the radially outer area of the planet carrier whereby, when the multi-disc brake is actuated in closing direction, the planet carrier becomes non-rotatably connected with the housing. To ensure a steady air play of the discs, the actuating device of the multi-disc brake has an automatic piston-resetting device. For this purpose, blind holes are situated in the housing in which engage clamping elements, which upon actuation of the brake, are displaced so that when the multi-disc brake is actuated in an opening direction, the clutch play remains steady. This kind of resetting device requires an expensive processing of the housing and the spring elements are heavily loaded. 
   The problem on which this invention is based is to provide a driveline for mobile vehicles which stands out by a steady operation of the brake. 
   SUMMARY OF THE INVENTION 
   The driveline, according to the invention, has a planetary transmission, the rotary part of which is non-rotatably connected with the housing when the multi-disc brake is actuated in the closing direction. To maintain uniform air play of the discs when the multi-disc brake is actuated in the opening direction, even with increasing wear of the discs, an automatic resetting device is situated in the piston. For this purpose, the piston has at least one hole in which at least one clamping element is located which supports itself upon one washer. The washer is axially movable between two stops and freely rotatable in the radial direction. The clamping elements preferably lie exclusively upon the washer whereby the clamping elements undergo absolutely no additional forces acting in a peripheral direction so that it is possible to use for actuating the multi-disc brake and an annular piston which requires no protection against twisting in the housing. Since no additional forces which could generate, for example, by the rotation of the piston, act upon the clamping elements, a steady operation of the automatic resetting device is ensured. On the washer upon which rest the clamping elements, tension of a recoil spring acts which forces back the piston when the multi-disc brake is actuated in the opening direction. But this is possible only as long as the washer abuts against its one stop. If the piston is actuated in the closing direction, the piston moves in the axial direction whereby the clamping elements situated therein likewise move in the axial direction and displace the washer against the spring tension. This is possible only between the two stops of the washer so that when the other stop of the washer is reached, the piston does move further in the closing direction of the multi-disc brake, but the clamping element supports itself upon the washer which is against its stop and slides into the piston. When the multi-disc brake is again actuated in the opening direction, the piston, in turn, returns back from within the stop of the washer due to the tension of the recoil spring whereby the spacing of the discs remains uniform. By situating the automatic resetting device on the inner area of the piston, an automatic resetting device is provided which is economical, consists of few simple parts and is easy to assemble. Since the piston is not connected with the housing in the radial rotating direction via the resetting device, it is not necessary to provide expensive parts for absorbing peripheral forces. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described, by way of example, with reference to the accompanying drawings in which: 
       FIG. 1  shows a driveline for mobile vehicles having an automatic resetting device; and 
       FIG. 2  shows detailed arrangement of the automatic resetting device. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   FIG.  1 : 
   It shows a section of one side of the drive axle with an axle pipe  1  which can be connected with the vehicle (not shown) and which has a funnel-shaped extension  2  which, via connecting elements  3 , is connected with the housing  4 . The input shaft  5  drives an inner central gear  6  of a planetary transmission  7  and can also be designed integral with the drive shaft. The input shaft is preferably connected with a differential (not shown). It is also possible to connect the input shaft with a prime mover, such as an electromotor or a hydromotor. The inner central gear  6  is in operative connection with the planetary gear  8 , which planetary gear  8  supports itself on the outer central gear  9  which is non-rotatably held. The outer central gear  9  is preferably non-rotatably situated by means of bolts  10  in the funnel-shaped extension  2  of the housing  4 . It is also possible to non-rotatably retain the outer central wheel  9  via a self-cutting toothing, a so-called “mouse toothing”, in the funnel-shaped extension  2  or the housing  4 . The planetary gear  8  is supported, via the planetary bearing  11 , upon the planet carrier  12 . The inner rotating discs  13 , of the multi-disc brake  14 , are non-rotatably disposed on the radial outer area of the planet carrier  12 , adjacent the planetary gear  8 . The outer discs  15  are non-rotatably located in the housing  4  or the funnel-shaped extension  2 . While the inner discs  13  rotate, cooling of the brake  14  occurs due to the centrifugal acceleration of the lubricant since the lubricant enters  13  an outer area of the planet carrier  12  by the inner disc, flows through the multi-disc brake and, in the area where the outer discs  15  are non-rotatably related, exits again in axial direction out of the multi-disc brake  14  being able to flow back via ducts  16 . The multi-disc brake  14  is preferably situated between the planetary gear  8  and the output flange  17 . A piston  18  is located between the multi-disc brake  14  and the output flange  17  which actuates the multi-disc brake  14  in a closing direction when pressure is applied in the space  19 . The piston  18 , when not actuated, is forced back by a recoil spring  20 . It is possible to allow the recoil spring  20  to act upon an automatic resetting device  21  situated in a radially inner area of the piston  18 . In this resetting device, a clamping  22  is disposed in the piston  18  which acts upon a washer  23  which is axially displaceable within a defined path and the axial path is limited by stops on both sides. Since the automatic resetting device  21  is not fixed in the axial direction, it also is unnecessary to fix the piston  18  in the radial direction. The piston  18  and the resetting device are preferably in the area of the first and second bearings. The planet carrier  12  has one journal  24  in the direction of the output flange  17  upon whose surface is situated the inner ring  25  of the second bearing  26 . The journal  24  is non-rotatably connected with the output flange  17  via a non-rotatable connection  27  such as a toothing or meander-shaped configuration of the surface or several bolts. Said non-rotatable connection  27  is located in a hole of the output flange  17 . Since the non-rotatable connection  27  is situated in the hole of the output flange  17 , its length can be optimally designed as required. The output flange  17  is supported in the housing  4  via a first bearing  28 . The inner diameter of the first bearing  28  is preferably larger than the second bearing  26 . A centering  29  is situated immediately adjacent the inner ring  25 . The output flange  17  is centered upon the journal  24  via said centering  29 . A bushing  31  is on the end of the journal  24 , remote from the planetary gear  8 , and centers the output flange  17  upon the journal  24 . The output flange  17  is thus centered via the bushing  31  and the centering  29  upon the journal  24  whereby the first bearing  28  and the second bearing  26  experience optimal operating conditions, since the output flange  17  cannot tip against the planet carrier  12 . The bushing  31  has a cup-shaped design and is braced, via connecting elements  32 , in the direction of the journal  24 , and the bushing  31 , via its axial face  33 , pressing the output flange  17  against the inner ring  25 . Since the inner ring  25  abuts against the planet carrier  12 , on one side, and against the axial surface  34  of the output flange  17 , on the other side, the first bearing  28  and the second bearing  26  can be easily assembled without expensive adjustment work. It is thus possible to use so-called “set-right bearings”. Since the bushing  31  and the connecting elements  32  are easily accessible from outside of the vehicle, the output flange  17  can be disassembled without removing the axle from the vehicle. Since only the first bearing  28  is on the output flange  17 , the output flange  17  can be disassembled without a great expenditure of force. This is possible since the inner ring  25  remains upon the planet carrier  12 . The bushing  31  can be easily disassembled by a pressing-off thread  35 . For protection of the connecting elements  32  and for easy sealing, the output flange  17  is closed by a lid  36  with a seal  37 . The output flange  17  is sealed relative to the housing  4  via a radial shaft seal ring  38 , a so-called “cassette seal”. In order to protect the seal  38  from pollution, the output flange  17  and the housing  4  are designed so that a labyrinth  39  generates. 
   FIG.  2 : 
   On the radial inner area of the piston  18  at least one hole  40  in which the clamping sleeve  22  is situated. Several holes  40  and clamping sleeves  22  preferably are uniformly distributed. The hole  40  can be a blind hole, but preferably is a through hole. Due to the pressurizing of the space  19 , if the piston  18  is moved in the closing direction of the brake  14 , the clamping sleeve  22  is likewise moved along in the direction of motion of the piston. The clamping sleeve  22  supports itself upon the washer  23  but preferably is not connected therewith so as not to have to support any additional forces in the peripheral direction. Due to the movement of the piston  18  and of the clamping sleeve  22 , the washer  23  is likewise moved against the tension of the spring  20  until the washer abuts with its stop  41 . The spring  20  is preferably fixed, in the axial direction, upon a guard ring  43  via a stop section  42 . In the embodiment shown, the washer  23  moves until the stop  41  abuts against the spring  20 . But other practical stops can also be used. If the washer  23  abuts with its stop  41  against the spring  20 , but the piston  18  still has not completely compressed the multi-disc brake  14 , and the piston  18  thus moves further until complete closing of the multi-disc brake  14  whereby the clamping sleeve  22  slides in the hole  40 . If the pressure in the space  19  is reduced from the state of the completely closed multi-disc brake, then, below a defined pressure, the tension of the spring  20  begins to move the washer  23  and thus the clamping sleeve  22  and the piston  18  in the opening direction. The piston  18  is moved only until the washer  23  abuts against its stop  44 . It is thus ensured that the play of the discs  13  and  15  remains the same in every closing state of the multi-disc brake  14 . 
   REFERENCE NUMERALS 
   
       
         1  axle pipe 
         2  funnel-shaped extension 
         3  connecting elements 
         4  housing 
         5  input shaft 
         6  inner central gear 
         7  planetary transmission 
         8  planetary gear 
         9  outer central gear] 
         10  bolt 
         11  bearing 
         12  planet carrier 
         13  inner discs 
         14  multi-disc brake 
         15  outer discs 
         16  ducts 
         17  output flange 
         18  piston 
         19  space 
         20  recoil spring 
         21  automatic resetting device 
         22  clamping sleeve 
         23  washer 
         24  journal 
         25  inner ring 
         26  second bearing 
         27  non-rotatable connection 
         28  first bearing 
         29  centering 
         30  end 
         31  bushing 
         32  connecting element 
         33  axial surface 
         34  axial surface 
         35  pressing-off thread 
         36  lid 
         37  seal 
         38  seal 
         39  labyrinth 
         40  hole 
         41  stop 
         42  stop section 
         43  guard ring 
         44  stop