Abstract:
The present invention prevents damage to the trolling motor and the mount by providing a shock-absorption system capable of lengthening to allow the motor assembly to pivot out of the path of an obstruction. Adjustable friction force maintains the clutch system assembly in its normal operating upright condition. When the trolling motor strikes an underwater object, the clutch friction is overcome and the clutch assembly lengthens, thus assuring that any damage is minimized.

Description:
FIELD OF THE INVENTION 
     The field of this invention relates generally to mounting structures for outboard motors and more particularly to a clutch slip-joint system that protects the trolling motor from damage when it strikes a submerged object. 
     BACKGROUND OF THE INVENTION 
     Trolling motors are generally suspended beneath the surface of water on a mounting structure affixed to the bow or stern of the boat. When trolling, it is not uncommon that a submerged object will be struck by the motor, causing extensive damage to the motor and mounting structure. In the past, various shock-absorption methods have been used to lessen and absorb the energy created by engagement of the motor with the obstacle. 
     U.S. Pat. No. 3,240,453 illustrates a shock-absorption system adapted for stern-mounted outboard drive motors. The motor is secured to the transom of the boat by swivel, tilt, and clamp brackets on a swivel pin. When the motor strikes an underwater object, the swivel bracket freely tilts out of the path of the object in an upward direction. The gear sector on the swivel bracket engages with the pinion attached to the clamp bracket that is affixed to the boat. Gear sector teeth are adapted to intermesh with corresponding teeth on the pinion, which actuates the clutch. Springs engage the clutch plate and clutch rings to absorb the kinetic energy. Tilting continues forward until the object is cleared, then motion is reversed until the gear segment engages the pinion and clutch system to freefall back to the motor&#39;s normal downward operating position. This is a complicated structure and it is exposed so that the gear assembly can jam. Protection is only afforded in one direction. 
     U.S. Pat. No. 4,734,068 demonstrates a mounting bracket system secured to the bow-mount supporting assembly. When the trolling motor strikes an underwater object, the force created will overcome the force typically maintained by compression springs on thrust pads and pins. The motor support bracket will pivot until the thrust pins reach the ends of the curved arcuate elongated slots on the cam surfaces. Upon release of the force on the compression springs, the thrust pins return to their normal operating position maintained by the compression springs. This design has several shortcomings. It is expensive to make curved slots. The metal-to-metal contact of the moving parts cain, over time and with exposure to saltwater or other corrosive environments, gall and make future movement less likely or impossible. The metal-to-metal contact also can result in paint scraping off, making for an unsightly appearance or promoting rust. 
     Accordingly, one of the objects of the present invention is to eliminate damage to trolling motors by providing an efficient shock-absorption system that entails easy assembly and carefree maintenance. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a slip-joint clutch assembly that is mounted on a fishing trolling motor. When the trolling motor collides with an underwater obstruction, this invention provides a simple, shock-absorbing mechanism that prevents damage to the motor by allowing the motor to swing under the boat. The clutch assembly consists of four principal parts, namely the upper channel, clutch shim, clutch channel, and mechanical fastener. The clutch channel is pivotally connected to the mount bracket. The clutch channel is slidably connected to the upper channel through the clutch shim. Preferably, a bolt is inserted through the spacer and the washers, and is secured by a nut attached to a clamping handle. The clamping handle allows adjustable bolt tension that can be tightened to hold the motor in place under normal operation. When the motor strikes an obstruction, the clutch friction is overcome, and the clutch assembly lengthens through the linear slots in the clutch channel. The motor will stay in this new angulated position under the boat until the clamping handle is turned, releasing the nut and the corresponding clamp force on the channels. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view showing the present invention in assembly and in use. 
     FIG. 2 is an exploded view of the tipper channel, clutch shim, clutch channel, spacer, spacer washers, and bolt. 
     FIG. 3 is a sectional elevational view of the clutch system assembled. 
     FIG. 4 is an exploded view of an alternative assembly of the upper channel, clutch shim, clutch channel, and bolt. 
     FIG. 5 is a side view of the clutch system assembly with the ball and spring mechanism. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Apparatus A in FIG. 2 is made of four principal components--an upper channel 2, a clutch shim 6, a clutch channel 8, and a mechanical fastener (preferably a stainless steel bolt 20, two plastic spacer washers 19, and a stainless steel clamping handle 22). While channels are preferred, different shapes can be used without departing from the purview of the invention. The other components are preferably made of aluminum or structural steel. Stainless steel may also be used. Upper channel 2 is a substantially U-shaped conduit with circular passageways 3 near the proximal end of both side panels of tipper channel 2. Two extensions 4 project from the distal end of both side panels of upper channel 2. The extensions are capable of attachment to the deck channel 5 (see FIG. 1). 
     Clutch shim 6 is substantially U-shaped and is preferably shorter in length than upper channel 2 and clutch channel 8. Clutch shim 6 is sized to be inserted into the underside of upper channel 2 and is further capable of accommodating clutch channel 8 into its underside, such that a selectively locking relationship can be formed. Shim 6 promotes sliding between channel 2 and channel 8, while separating these two channels to prevent galling, and to provide some lubrication to facilitate relative movement between the channels. It is preferably 6/6 nylon. Circular passageways 7 near the proximal end of both side panels on clutch shim 6 are present. Clutch channel 8 is a substantially U-shaped conduit that is longer in length than clutch shim 6 and shorter in length than upper channel 2. An elongated linear slot 10 is centrally located on both side panels of clutch channel 8. Two extensions 12 project from the distal end of clutch channel 8. The extensions 12 are capable of attachment to the upper member of the trolling motor assembly 13 (see FIG. 1) through two circular passageways 14 located at the tips of the two extensions 12. 
     A tubular member 18, capable of maintaining a uniform distance space, is inserted into the underside of clutch channel 8, clutch shim 6, and upper channel 2 while assembled in their selectively locking relationship. Tubular member 18 is fitted with preferably two plastic shoulder washers or flat plastic washers at its ends to ensure that galling and paint scraping do not occur. Channels 2 and 8 and shim 6 are at least partially nested. The circular passageways on upper channel 3, clutch shim 7 passageways, and elongated linear slots 10 are aligned with tubular member 18 and the two washers 19 to accommodate bolt 20, longer in length than the assembled apparatus A (see FIG. 3). The head of bolt 20 and a clamping handle 22, capable of engaging the threaded body of bolt 20, may be tightened in a circular fashion until the desired friction between channels 2 and 8 is achieved on the assembled apparatus. 
     Under normal operating conditions, the motor assembly is maintained in an upright position by the compression exerted by the clamping handle 22. When the trolling motor assembly strikes an underwater object, kinetic energy is created and the assembled apparatus A absorbs most of the shock. When the clutch frictional forces between channel 2 and shim 6, and channel 8 and shim 6 are overcome, the clutch assembly releases (slips). Clutch channel 8 slides forward on shim 6 via the elongated linear slots 10 to extend the upper member of mount 13 forward, thereby allowing bracket 70 to pivot on bow arm 9 attached to the deck channel 5. Bow arm 9 does not move when clutching. This action, in turn, swings the trolling motor under the boat. Reverse motion is also possible. 
     The clutch assembly could be made to lengthen and/or shorten in a forward or reverse manner using an alternate mechanism (see FIG. 4). Upper channel 24 is substantially a U-shaped conduit that is longer in length than clutch channel 32. The distal end of upper channel 24 has a circular passageway 26 centrally located on the upper panel of upper channel 24. Two extensions 28 with two circular passageways 30 on the side panels of the extensions 28 are located on the proximal end of upper channel 24 and are capable of attachment to deck channel 5. 
     A clutch channel 32, sized to be inserted into the underside of clutch shim 40, is, in turn, inserted into the underside of upper channel 24. Clutch channel 32 is similarly a substantially U-shaped conduit. When assembled, they are nested at least in part. Two extensions 34 with two circular passageways 36 are capable of attachment to the column support of motor assembly 13. An elongated linear slot 38 is located on the upper panel of clutch channel 32. 
     Clutch shim 40, preferably 6/6 nylon or rubber or plastic material having high durability and lubricating capabilities, has elongated linear slot 42 similar in size and shape to linear slot 38. Clutch shim 40 is inserted for support into the underside of upper channel 24 and over clutch channel 32 to form a selectively locking relationship with one another. A mechanical fastener bolt and nut may be used to obtain the desired friction to maintain the motor assembly in its normal upright operating condition. When the trolling motor strikes the underwater object, the clutch friction is overcome between channel 32 and shim 40, and clutch channel 32 moves in a forward manner or in a reverse manner, depending on the direction of travel upon impact. 
     A ball and spring mechanism may be used to locate the clutch system at mid-point of travel to assure that the motor is in the proper upright normal running position (see FIG. 5). A ball 48 and spring 46 slip into a detent 44 to audibly or through sensory communication alert the operator that the motor is in an upright position and that bolt 20 and clamping handle 22 can then be tightened on elongated slots 10, 38, and 42. When the trolling motor strikes the submerged object, the friction on bolt 20 and clamping handle 22 is overcome. Detent 44 is moved in a forward manner due to the clutch action, which compresses ball 48 against spring 46 and into depression housing 50. 
     The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.