Patent Publication Number: US-6708430-B2

Title: Trencher chain bar and safety guide

Description:
TECHNICAL FIELD 
     This invention relates to a trencher having a roller chain carried on a chain bar. More particularly, this invention relates to the structure of the chain bar and to a safety guide that is adjustable in concert with the chain bar. 
     BACKGROUND OF THE INVENTION 
     Trenchers are known having an elongated chain bar that extends outwardly from the trencher frame in a cantilever manner. Such trenchers include a roller chain that is configured to cut, dig or otherwise remove material such as dirt or soil to create an elongated trench in the ground. The roller chain loops around the chain bar. The trencher frame carries a motor for powering the roller chain so that digging or cutting teeth provided on the roller chain will cut or dig soil as the roller chain is driven around and around the chain bar. 
     In prior art trenchers, the chain bar is typically formed of two major pieces that are secured together. The first piece comprises a stub fixed to the trencher frame. The second piece is an elongated boom having a socket at one end telescopically inserted over the stub. The boom is clamped to the stub by various bolts which pass through the boom and over the top and bottom surfaces of the stub. 
     Because the bolts used to clamp the boom to the stub press against the top and bottom surfaces of the stub, the height of the stub is quite small to accommodate the thickness of the bolts. Thus, for a given sized boom and drive sprocket carried on the boom, the attachment between the stub and the boom is not as robust or durable as might be desired due to the small size of the stub. Thus, a better way of attaching the boom to the stub is desirable in the art. 
     In addition, prior art trenchers have typically been built such that the chain bar is located in a first or normal position on one side of the frame. A safety guide or bar has been provided above this first position of the chain bar. In some prior art trenchers, the chain bar can be moved to a second or offset position on the other side of the frame. However, the safety guide does not move with the chain bar as it is typically installed only above the first position of the chain bar and cannot be installed in any other position. Thus, when the chain bar is moved to its second or offset position, it is used in this position without the safety guide being located above it, which is disadvantageous. 
     SUMMARY OF THE INVENTION 
     One aspect of this invention relates to a trencher for digging trenches. The trencher comprises a trencher frame. A chain bar is secured at one end to the trencher frame to extend outwardly from the trencher frame in a cantilever manner. An endless chain having digging teeth is provided with the endless chain being carried on the chain bar. The chain bar comprises a base member secured to the trencher frame which base member carries a stub having a longitudinal axis, an elongated boom having a socket at one end which socket is slipped over the stub of the base member, a slot in the stub with the slot extending parallel to the longitudinal axis of the stub, and at least one bolt passing through the boom and the slot to secure the boom to the stub. 
     Another aspect of this invention relates to a trencher for digging trenches. The trencher comprises a trencher frame. A chain bar is secured at one end to the trencher frame to extend outwardly from the trencher frame in a cantilever manner. An endless chain having digging teeth is provided with the endless chain being carried on the chain bar. A safety guide is secured at one end to the trencher frame to extend outwardly from the trencher frame in a cantilever manner. Both the chain bar and the safety guide are adjustable on the trencher frame between two laterally spaced positions with the safety guide overlying the chain bar in both of the two laterally spaced positions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This invention will be described hereafter in the Detailed Description, taken in conjunction with the following drawings, in which like reference numerals refer to like elements or parts throughout. 
     FIG. 1 is a side elevational view of a trencher which utilizes a roller chain to dig a trench with such roller chain being carried on a chain bar in an endless fashion, the trencher being shown in FIG. 1 in operation in the act of digging a trench; 
     FIG. 2 is perspective view of a trencher according to this invention, particularly showing the chain bar and the safety guide in a first position on one side of the trencher frame, with the chain being omitted from FIG. 2 for clarity; 
     FIG. 3 is perspective view of the trencher shown in FIG. 2, but illustrating the trencher from the side which is opposite to the side that is shown in FIG. 2, with the chain being omitted from FIG. 3 for clarity; 
     FIG. 4 is a perspective view of the base member and stub that forms part of the chain bar of the trencher shown in FIG. 2; and 
     FIG. 5 is perspective view of a trencher according to this invention, particularly showing the chain bar and the safety guide in a second, offset position on the opposite side of the trencher frame from that which is depicted in FIG. 1, with the chain, drive sprocket and drive motor being omitted from FIG. 5 for clarity. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a trencher  2  in operation. Trencher  2  is carried on a set of lift arms  4 , only one lift arm  4  being shown in FIG. 1 with the other lift arm  4  being hidden in FIG.  1 . Lift arms  4  form part of a compact utility loader  100 . Compact utility loader  100  is capable of releasably coupling various attachments, such as trencher  2 , to the lower ends of lift arms  4  utilizing known quick attachment systems. When a trencher  2  is attached to lift arms  4  of compact utility loader  100 , the overall combination is referred to as a trencher  2 . Obviously, trencher  2  could also be a dedicated, single purpose machine in which trencher  2  is normally non-removably attached to a loader or other self-propelled frame. 
     Compact utility loader  100  as shown herein is comprised of a frame supported by front wheels  101  and rear wheels  102 . An engine or motor (not shown) is carried on the loader frame to provide power. Compact utility loader  100  may also include a platform  103  on which the operator stands to operate loader  100 , Alternatively, platform  103  could be removed and the operator could simply walk behind loader  100 . The operation of lift arms  4  and the wheels  101  and  102  are controlled by operator controls  104 . Loader  100  may be the type such as those manufactured and sold by The Toro Company, the assignee of this invention, as the DINGO brand compact utility loader. 
     As shown in FIG. 1, trencher  2  comprises a chain bar  5  that guides an endless roller chain  10 . Roller chain  10  digs a trench by removing dirt and similar material from the ground as chain  10  is driven. Chain  10  includes a plurality of digging teeth  14  which are carried on chain  10  at spaced locations. Trencher  2  can be positioned against or in the ground by pivoting lift arms  4  about a first pivot point  7  on loader  100  and also by pivoting trencher  2  about a second pivot point  8  on the lower ends of lift arms  4 . 
     Chain bar  5  includes a drive sprocket  3  at one end of bar  5  and an idler member  6  located at the opposite end of bar  5 . Drive sprocket  3  is connected to and driven by a suitable drive system, such as a hydraulic motor  12 , that is powered by the engine of loader  100 . The drive system rotates drive sprocket  3 , which in turn engages and drives chain  10  in an endless path around drive sprocket  3  and idler member  6 . 
     Referring now to FIGS. 2-4, trencher  2  includes a frame  20  from which chain bar  5  extends in a cantilever manner. When trencher  2  is built as an attachment for a loader  100 , frame  20  also includes a quick attachment mount  22  that allows trencher  2  to be quickly and easily attached to loader arms  4 . The shape and structure of frame  20  can obviously vary as well as the type of quick attachment mount  22  used to couple trencher  2  to loader  100 . In addition, quick attachment mount  22  could be deleted when trencher  2  is part of a dedicated, single purpose machine. 
     Chain bar  5  comprises a base member  24  to which an outwardly extending boom  26  is secured in a cantilever manner. Base member  24  preferably comprises a single casting as shown in FIG.  4 . Base member  24  includes a flange or rear wall  28  having a plurality of holes  30  extending therethrough. See FIG. 5. A plurality of bolts  32  or similar securing members can be used to pass through holes  30  to bolt base member  24  to trencher frame  20 . FIG. 3 illustrates bolts  32  passing through holes  30  in rear wall  28  of base member  24  to bolt base member  24  to trencher frame  20 . 
     Trencher frame  20  includes first and second sets  34   a  and  34   b  of mounting holes which have a hole pattern that is the same as the pattern of holes  30  in rear wall  28  of base member  24 . These sets  34   a  and  34   b  of mounting holes are transversely or laterally spaced apart on trencher frame  20  so that one set  34   a  of mounting holes is adjacent one side of trencher frame  20  and the other set  34   b  of mounting holes is adjacent the other side of trencher frame  20 . FIGS. 2 and 3 illustrate chain bar  5  mounted on trencher frame  20  in a first position on one side of trencher frame  20  using a first set  34   a  of the mounting holes. FIG. 5 illustrates chain bar  5  mounted on trencher frame  20  in a second, laterally offset position using the second set  34   b  of mounting holes, with the attachment bolts  32  having been deleted from FIG. 5 to better illustrate holes  30  in rear wall  28  of base member  24 . 
     Similarly, trencher frame  20  comprises first and second sets  36   a  and  36   b  of mounting holes for a safety guide  38 . The dual sets  36   a  and  36   b  of safety guide mounting holes overlie the dual sets  34   a  and  34   b  of base member mounting holes to allow safety guide  38  to be installed above chain bar  5  regardless of what side of trencher frame  20  chain bar  5  is mounted on. Thus, as shown in FIGS. 2 and 3, when chain bar  5  is mounted on one side of trencher frame  20 , safety guide  38  can be mounted above chain bar  5  using the first set  36   a  of safety guide mounting holes and a plurality of bolts  40  for bolting safety guide  38  to trencher frame  20 . When chain bar  5  is laterally offset on trencher frame  20  and is mounted on the other side of trencher frame  20 , safety guide  38  can similarly be moved over and be bolted to trencher frame  20  using the second set  36   b  of safety guide mounting holes. See FIG.  5 . Thus, safety guide  38  can remain in place above chain bar  5  regardless of which side of trencher frame  20  carries chain bar  5 . 
     The entire safety guide  38  is shown in FIGS. 2,  3  and  5 . The front of safety guide  38  carries mounting holes  42  to which an optional crumber attachment  43  can be bolted if so desired. FIG. 1 shows the safety guide  38  with crumber attachment  43  secured thereto while FIGS. 2,  3  and  5  illustrate safety guide  38  without a crumber attachment  43 . Note that safety guide  38  and crumber attachment  43  per se are well known in the art and their structure need not be specifically described herein. This invention does not relate to safety guide  38  per se such that the structure of safety guide  38  could be varied. Only one aspect of this invention relates to the dual sets  36   a  and  36   b  of safety guide mounting holes to allow safety guide  38  to be mounted on opposite sides of trencher frame  20  to be laterally adjustable in concert with the lateral adjustment of chain bar  5 . 
     Returning now to FIG. 4, another portion of base member  24  comprises a forwardly extending mounting peg or stub  50 . Mounting stub  50  has a rectangular cross-section. An elongated mounting slot  52  passes through stub  50  along a longitudinal axis of stub  50  indicated as  1  in FIG.  4 . This longitudinal axis  1  is parallel to the intended direction of elongated chain bar  5 . Slot  52  also passes completely through the width of stub  50 , which width is indicated as w in FIG. 4, such that slot  52  is accessible from both sides of stub  50 . 
     Elongated boom  26  of chain bar  5  is mounted to stub  50  by forming boom  26  with a socket at one end to allow the socket to be telescopically inserted over stub  50 . After this has been done, chain  10  can be installed around drive sprocket  3  and idler member  6  and a longitudinal adjustment screw  54  can be tightened to take up the slack in chain  10 . Boom  26  can then be secured to stub  50  by a plurality of bolts  60  which can be inserted through the sides of boom  26  such that bolts  60  pass through central slot  52  in stub  50 . When nuts  58  are tightened on the opposite ends of bolts  60 , boom  26  will then be secured in place to stub  50  of base member  24  of secure chain bar  5  to trencher frame  20 . 
     Using a central mounting slot  52  in stub  50  allows the height of stub  50 , indicated as h in FIG. 4, to be maximized for a given height of boom  26  or for a given diameter of drive sprocket  3 . This is an improvement over the prior art in which the stub height was relatively small to allow bolts  60  to pass over the top and bottom surfaces of stub  50 . Accordingly, chain bar  5  disclosed herein is stronger and more durable given the greater height of stub  50  to which boom  26  is attached. 
     Various modifications of this invention will be apparent to those skilled in the art. For example, while two laterally offset positions have been shown for both chain bar  5  and safety guide  38 , more than two laterally offset positions could be used for each. Boom  26  is made from a plurality of side plates secured to top and bottom plates, but boom  26  could be integrally cast if so desired. Thus, the scope of this invention is to be limited only by the appended claims.