CA2134857C - Energy dampening drawbar - Google Patents
Energy dampening drawbarInfo
- Publication number
- CA2134857C CA2134857C CA002134857A CA2134857A CA2134857C CA 2134857 C CA2134857 C CA 2134857C CA 002134857 A CA002134857 A CA 002134857A CA 2134857 A CA2134857 A CA 2134857A CA 2134857 C CA2134857 C CA 2134857C
- Authority
- CA
- Canada
- Prior art keywords
- drawbar
- shank
- energy dampening
- cushion
- block
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60D—VEHICLE CONNECTIONS
- B60D1/00—Traction couplings; Hitches; Draw-gear; Towing devices
- B60D1/48—Traction couplings; Hitches; Draw-gear; Towing devices characterised by the mounting
- B60D1/50—Traction couplings; Hitches; Draw-gear; Towing devices characterised by the mounting resiliently mounted
Abstract
An energy dampening drawbar for use with receiver hitches and specialty types of hitches is described as including an elongated hollow shank having slots on opposite sides. A first cushion block is located within the shank and has a portion of the first cushion block adjacent one surface of a pin block. The pin block has a hole that aligns with a portion of the two slots. A second cushion block is located within the shank adjacent another surface of the pin block. A first restraint prevents longitudinal travel within the shank by the first cushion block. A second restraint prevents longitudinal travel within the shank by the second cushion block.
A plate is attached to one end of the shank to provide a surface for attaching a trailer coupling.
A plate is attached to one end of the shank to provide a surface for attaching a trailer coupling.
Description
21348~7 ENERGY DAMPENING DRAWBAR
R~K~ROUND OF TaE INVENTION
1. F~eld of the Invention:
The present invention, in general, relates to drawbars for towing a trailer and, more particularly, to a drawbar that will dampen the forces of shock and impact that occur between a towing vehicle and a trailer being towed.
A trailer, like all objects, has inertia. When it is at rest, it tends to remain at rest unless acted upon by ~ome force to the contrary. Similarly a trailer in motion tend~ to remain in motion unless also acted upon by a force to the contrary.
A contrary force is provided by irregularities in a road surface, by gravity and by the towing vehicle when either accelerating or braking. The trailer and towing vehicle are connected together by any of a variety of hitch arrangements; a ball type of hitch coupling arrangement being the most common, and a pintle type of hitch coupling is used sometimes for towing heavier trailers.
~13~8S7 Any hitch couplinq i8 a mechanical device having mechanical tolerances between its component parts. The~e tolerances produce a cumulative gap between the component parts that is more commonly referred to as "slackn.
The slack between the component parts of a trailer hitch produces a shock impulse when accelerating as a result of having the towing vehicle move ~lightly forward before the trailer begins to move. As such, a shock impulse occurs momentarily when all of the existing slack has been taken up by the forward motion of the towing vehicle, and a sudden transference of kinetic energy occurs at the towing interface in the form of an impact.
Similarly when decelerating, either the towing vehicle or the trailer will begin to slow first, depending upon whether trailer brakes are used and how they are adjusted, and once again, when all of the slack has been taken up, an impact will occur.
The impact is perceived by occupants of the towing vehicle as a jolt. The severity of the jolt is proportional to the differences in inertia that arise between the towing vehicle and the trailer. A jolt will occur whenever an imhalance occurs between the inertia of the trailer and the inertia of the towing vehicle.
213~8~7 -The seve~ity of the jolt is representative of the balancing of kinetic energy between the towing vehicle and the trailer. Jolts of varying severity occur during acceleration, deceleration and also during normal transit as slight differences in velocity between the towing vehicle and the trailer develop.
Since it is not a practical option to eliminate all slack by reducing the sum total of all of the mechanical tolerances of a trailer hitch and coupling to zero, arrangements that will absorb and dampen shock impulses are preferred.
Such structures, in general, utilize dampening techniques.
Mechanical trailer hitch dampening techniques will smoothly and temporarily absorb some of the kinetic energy, and then, smoothly return that energy back to the towing vehicle and to the trailer, thereby lessening the perception of a jolt having occurred by towing vehicle occupants.
Prior trailer hitch dampening arrangements, that smooth the transfer of energy between a trailer and towing vehicle, tend to be somewhat complex in construction and, accordingly, are expensive.
Prior dampening arrangements are not readily adaptable to accommodate trailers of varying weight, nor are they readily adaptable for use with common types of trailer hitches, such as for 21348~7 use with receiver types of hitches where a variety of drawbars are inserted.
Accordingly, there exists today a need for an energy dampening drawbar capable of dampening the shock impulses that arise between a trailer and a towing vehicle that is adaptable for use with standard types of receiver hitches and is also adaptable for use with specialty types of receiver hitches including wide ranging types of hitches, ball hitches, and pintle hitches.
R~K~ROUND OF TaE INVENTION
1. F~eld of the Invention:
The present invention, in general, relates to drawbars for towing a trailer and, more particularly, to a drawbar that will dampen the forces of shock and impact that occur between a towing vehicle and a trailer being towed.
A trailer, like all objects, has inertia. When it is at rest, it tends to remain at rest unless acted upon by ~ome force to the contrary. Similarly a trailer in motion tend~ to remain in motion unless also acted upon by a force to the contrary.
A contrary force is provided by irregularities in a road surface, by gravity and by the towing vehicle when either accelerating or braking. The trailer and towing vehicle are connected together by any of a variety of hitch arrangements; a ball type of hitch coupling arrangement being the most common, and a pintle type of hitch coupling is used sometimes for towing heavier trailers.
~13~8S7 Any hitch couplinq i8 a mechanical device having mechanical tolerances between its component parts. The~e tolerances produce a cumulative gap between the component parts that is more commonly referred to as "slackn.
The slack between the component parts of a trailer hitch produces a shock impulse when accelerating as a result of having the towing vehicle move ~lightly forward before the trailer begins to move. As such, a shock impulse occurs momentarily when all of the existing slack has been taken up by the forward motion of the towing vehicle, and a sudden transference of kinetic energy occurs at the towing interface in the form of an impact.
Similarly when decelerating, either the towing vehicle or the trailer will begin to slow first, depending upon whether trailer brakes are used and how they are adjusted, and once again, when all of the slack has been taken up, an impact will occur.
The impact is perceived by occupants of the towing vehicle as a jolt. The severity of the jolt is proportional to the differences in inertia that arise between the towing vehicle and the trailer. A jolt will occur whenever an imhalance occurs between the inertia of the trailer and the inertia of the towing vehicle.
213~8~7 -The seve~ity of the jolt is representative of the balancing of kinetic energy between the towing vehicle and the trailer. Jolts of varying severity occur during acceleration, deceleration and also during normal transit as slight differences in velocity between the towing vehicle and the trailer develop.
Since it is not a practical option to eliminate all slack by reducing the sum total of all of the mechanical tolerances of a trailer hitch and coupling to zero, arrangements that will absorb and dampen shock impulses are preferred.
Such structures, in general, utilize dampening techniques.
Mechanical trailer hitch dampening techniques will smoothly and temporarily absorb some of the kinetic energy, and then, smoothly return that energy back to the towing vehicle and to the trailer, thereby lessening the perception of a jolt having occurred by towing vehicle occupants.
Prior trailer hitch dampening arrangements, that smooth the transfer of energy between a trailer and towing vehicle, tend to be somewhat complex in construction and, accordingly, are expensive.
Prior dampening arrangements are not readily adaptable to accommodate trailers of varying weight, nor are they readily adaptable for use with common types of trailer hitches, such as for 21348~7 use with receiver types of hitches where a variety of drawbars are inserted.
Accordingly, there exists today a need for an energy dampening drawbar capable of dampening the shock impulses that arise between a trailer and a towing vehicle that is adaptable for use with standard types of receiver hitches and is also adaptable for use with specialty types of receiver hitches including wide ranging types of hitches, ball hitches, and pintle hitches.
2. Description of Prior Axt:
Energy dampening hitch systems, in general, are known. For example, U.S. patent No. 4,515,387 to Schuck that issued May 7, 1985, describes a hitch with a swiveling tongue having cushions to absorb the shock loading.
While the structural arrangements of various types of drawbar devices, at first appearance, have similarities with the present invention, they differ in material respects. These differences, which will be described in more detail hereinafter, are essential for the effective use of the invention and which admit of the advantages that are not available with the prior devices.
213~8~7 OBJECTS AND SU~ARY OF TIIE I~VENTION
It is an important object of the present invention to provide an energy dampening drawbar the reduces the shock impulse occurring between a towing vehicle and a trailer.
It is also an object of the invention to provide an energy dampening drawbar that helps to smooth and cu~hion the ride as perceived by occupants of a vehicle when towing a trailer.
Another object of the invention is to provide an energy dampening drawbar that i8 suitable for use with a variety of receiver type hitches.
Still another object of the invention is to provide an energy dampening drawbar that is suitable for use with specialty type hitches.
Briefly, an energy dampening drawbar for use with different types of hitches, that is constructed in accordance with the principle~ of the present invention, has an elongated hollow shank with two slots, one on each side. A pin block, having a hole communicating with both slots, is located within the elongated shank between first and second impact cushioning devices. A
~13~857 trailer can be attached to one end of the drawbar and a towing vehicle can be attached to the drawbar at the hole in the pin block between the two slot~ in the ~hank.
BRI~F DESCRIPTION OF T~E ~RAWI~G8 FIG. 1 is a side view of a preferred energy dampening drawbar.
FIG. 2 is a cross sectional view taken on the line 2-2 in FIG. 1 FIG. 3 is a cross sectional view taken on the line 3-3 in FIG. 1 FIG. 4 is a side view showing additional detail of an end bloc~
pin as used in the drawbar.
Other feature~, objects and advantages of the pre~ent invention will become more readily apparent from the following detailed description of the presently preferred embodiment, which i~
described in conjunction with above identified FIGURES of drawings which illustrate component parta a~ an aid to the description.
D~TAlT-~n DESCRIPTION OF T~E INVENTION
Referring to FIa. 1 and to F~a. 2 an energy da~r6n;ng drawbar, i~ identified, generally, by the numeral 10, and is illu~trated as ~134857 an aid to the following detailed description. An elongated shank 11 is constructed of square tubing 80 that it will fit into receiver types of hitches.
While ~quare tubing i9 preferred, for the reason identified above, the ~hank 11 can be formed from either round, rectangular, or polygonal stock when it is to be used with more specialized types of hitches.
The shank 11 has two elongated slots 12a and 12b located one on one side of the shank 11 and one slot on the opposite side. Only the one slot 12a is visible in FIG. 1 with the other slot 12b being present on the oppo~ite surface of the shank 11 and in alignment with the slot 12a.
A plate 13 is welded to one end of the shank 11. The opposite end of the shank 11 is open to provide for both assembly and maintenance access to the various component parts that are located inside the shank 11 of the drawbar 10.
The plate 13 has a hole 13a therein for accepting a hitch ball that is not shown in this view. A first cushion block 14 having a eize and ~hape eo that it will fit within the ehank 11 from the open end and rest against the ball plate 13. The ball plate 13 - 213~8~7 serves as a r~straint to prevent further movement of the first cushion block 14 within the shank 11 toward the ball plate 13.
A pin block 15 is contiguous with the first cushion block 14 and has a hole 16 in aligned with the elonqated slots 12a and 12b.
A second cushion block 17 having a size and shape to fit within the hollow shank 11 and is contiguous with the pin block 15.
A block 18 fits within the ~hank 11 and is contiguous with the second cushion block 17.
Referring to FIG. 3 and FIG. 4, the block 18 has a hole 19 extending through it. The shank 11 also has two holes 20a and 20b that align with the hole 19 when the block 18 is inserted in the shank 11.
A pin 21 through the holes 20a and 20b of the shank ll and through the hole 19 secures the block 18 in position within the shank 11. The block 18 is a restraint to prevent the second cushion block 17 from further movement within the shank 11.
The pin 21 is secured in position by a threaded set screw 22 that is threaded in the block 18. The ~et ~crew 22 i~ tightened until it bears against a recess 23 formed in the pin 21. The set ~1348~7 screw 22, after being firmly tightened, secures the block 18 in position within the hollow shank 11.
Since the purpose of the energy dampening drawbar 10 is to substantially eliminate shock impulses between the towing vehicle and the trailer, it is important that the component parts do not introduce additional slack that might aggravate the situation.
After assembly, a compressive force, such as is obtained from a press, i8 applied through the open end of the shank 11 against the block 18. The purpose of applying a compressive force is to remove any slack between the component parts- within the shank 11 and to also apply a slight compressive pre-load to the first and second cushion blocks 14 and 17. The amount of pre-load is selected according to the energy dampening characteristics desired for a particular drawbar 10.
The first cushion block 14 and the second cushion block 17 are constructed according to the energy dampening characteristics that are de~ired for a particular drawbar 10. The first and second cushion blocks 14 and 17, preferably are constructed of an elastomeric material, such as, for example, natural and synthetic rubber and urethane. The material that i~ ~elected must provide a desired resistance to compression.
~13~857 For example, the second cushion block 17 experiences all of the loading that is normally associated with towing a trailer and, as such, is usually under a considerable compressive load.
Therefore, the elastomeric material selected for the second cushion block 17 will have a higher durometer value than that selected for the first cushion block 14.
Certain special drawbar uses require exactly the opposite selection of properties for each of the cushion blocks 14 and 17.
The shape and size of each cushion block 14 and 17 also are varied to accommodate various types of material used in the construction of the shank 11 and, also, to vary the damp~ni ng characteristics for the drawbar 10. Each cushion block 14 and 17 is formed of a particular elastomeric material having a ~ize and shape to permit each cushion block 14 and 17 to be inserted into the hollow chamber formed by the shank 11.
For certain situations, a generally cylindrical shape is preferred to permit each cushion block 14 and 17 to deform during compression so as to accommodate the available space within a typical shank 11 having a square cross section. Each cushion block 14 snd 17 ie con~tructed, when required, to have a tapered end a~
shown in FIG. 1 and FIG. 2.
In certain situations, such as when it is desirable to obtain a progressive and variable dampening characteristic, the desired rate of dampening may not be obtAin~hle by the use of only one type of elastomeric material for each of the cushion block~ 14 and 17.
In such situations, each cushion block 14 and 17 is replaced by a plurality of cushion block~ on either side of the pin block 15.
When a plurality of cushion blocks are used, each block is selected to provide a particular desired dampening characteristic.
A modification to which the structure of the invention is adaptable permits the ela~tomeric material of either cushion block 14 and 17 to be replaced by a coil spring to provide the desired dampe~ing characteristics for certain specialized situations.
In another modification, the slots 12a and 12b, or the plug holes 20a and 20b are located elsewhere along the shank 11, or they are located on a different surface plane of the shank 11 tube as is required to ~atisfy use of the drawbar 10 with specialized types of hitche3, including certain types of wide ranging hitches.
Similarly, if desired, a separate restraint is affixed to the shank 11 and is used to prevent motion by the first cushion block 14, instead of relying upon the ball plate 13 to restrain the first cu~hion block 14.
~134857 -Operation:
In use, the drawbar 10 i8 in~erted into a receiver tube that is a part of the hitch mechanism of a towing vehicle, the shape of the receiver tube is similar, generally, to that of the elongated hollow shank 11. The interior dimensions of most receiver tubes are somewhat larger than the outside dimensions of the shank 11 to permit the shank 11 to be inserted quite readily into the receiver tube of a hitch mechanism.
When a conventional drawbar is used with many receiver tubes of today's hitches, a hitch pin is u~ed to secure the conventional drawbar within these receiver tubes. Normally, the hitch pin passes through a pair of holes that are provided in a receiver tube and, also, through corresponding holes in the conventional drawbar that align with the receiver tube holes.
However, when the energy dampening drawbar 10 of the present invention is used, the drawbar 10 is inserted into a receiver tube and a hitch pin is inserted through the holes in the receiver tube and through the slots 12a and 12b of the shank 11 and also through the hole 16 of the pin block 15.
Whon the dr~wbo.r 10 of th- invontion i- aon-truatod, th- hole 16 of the pin block 15 is within the opening of the slots 12a and ~134857 -12b. This permits the hole 16 to be aligned with holes in a receiver tube when the drawbar 10 i9 inserted. A hitch pin of any suitable type is inserted, and the drawbar 10 is secured within the receiver tube.
Should a failure of certain critical component part~ of the drawbar 10 occur, built-in safeguard~ en~ure that the drawbar 10 will not uncouple from the receiver tube. For example, if the end block pin 21 were to fail or to become dislodged from the block 18, the block 15 would be free to slide unimpeded longit~l~in~lly in a direction towards the open end of the shank 11. However, the hitch pin would eventually come into contact with one end of the two slots 12a and 12b, thereby preventing further travel by the block 15 and, thuæ, securing the drawbar 10 in the receiver tube during such a failure.
A hitch coupler on a trailer i~ connected to an appropriate hitch ball that normally passes through the hole 13a in the ball plate 13 to secure the trailer to the vehicle for towing.
When towing, the transfer of the force occurring between the towing vehicle and the trailer is eventually transmitted through the hitch coupling and to the eh~nk 11 of the drawbar 10. Ae the towing vehicle accelerates initially, the shank 11 is pulled in a ~13~857 direction gen~rally out of the receiver tube. The shank 11 is able to travel longitudinally within a maximum range of motion as determined by the length of the slot~ 12a and 12b. The block 15 is held stationary relative to the holes in a receiver tube by the hitch pin passing throuqh.
During acceleration, as the shank 11 is pulled slightly out from a receiver tube, the pin block 15 will bear against the second cushion block 17, which is compressed even further. The amount of the compression that is experienced by the second cushion block 17 is in proportion to the force applied by the towing vehicle and to the inertia of the trailer. A greater or lesser applied force will result in the greater or lesser proportional longitudinal motion of the shank 11 relative to the pin block 15.
The specific distance that the shank 11 actually moves relative to the pin block 15 for any given applied force is determined primarily by both the elastomeric and deformation properties of the second cushion block 17.
The act of compressing the second cushion block 17 reduces the severity of a jolt that would otherwise have been felt by occupants in the towing vehicle. During normal tranHit, the ~econd cu~hion block 17 will either relax or compress periodically in response to - ~1348~7 the exerted fQrces.
A similar process occur~ during deceleration of the towing vehicle, where the first cushion block 14 is compressed in proportion to the forces experienced. The functioning of the first cushion block 14 complements that of the second cushion block 17.
During transit, therefore, the first cushion block 14 will either relax or compress periodically in response to the exerted forces.
The compression and deformation of either of the cushion blocks 14 and 17 absorbs shock impulses and, later, returns the energy so absorbed during the subsequent relaxation and e~p~n~ion of either of the elastomeric cushion blocks 14 or 17. Shock impulses are decreased substantially by this action, and the ride as perceived by occupants is smoothed, and the wear and tear upon respective component parts is lessened also.
The invention has been shown, described and illustrated in substantial detail with reference to the presently preferred embodiment. It will be understood by those skilled in this art that other and further changes and modifications may be made without departing from the spirit and scope of the invention, which i8 defined by the claims appended hereto.
What is claimed is:
Energy dampening hitch systems, in general, are known. For example, U.S. patent No. 4,515,387 to Schuck that issued May 7, 1985, describes a hitch with a swiveling tongue having cushions to absorb the shock loading.
While the structural arrangements of various types of drawbar devices, at first appearance, have similarities with the present invention, they differ in material respects. These differences, which will be described in more detail hereinafter, are essential for the effective use of the invention and which admit of the advantages that are not available with the prior devices.
213~8~7 OBJECTS AND SU~ARY OF TIIE I~VENTION
It is an important object of the present invention to provide an energy dampening drawbar the reduces the shock impulse occurring between a towing vehicle and a trailer.
It is also an object of the invention to provide an energy dampening drawbar that helps to smooth and cu~hion the ride as perceived by occupants of a vehicle when towing a trailer.
Another object of the invention is to provide an energy dampening drawbar that i8 suitable for use with a variety of receiver type hitches.
Still another object of the invention is to provide an energy dampening drawbar that is suitable for use with specialty type hitches.
Briefly, an energy dampening drawbar for use with different types of hitches, that is constructed in accordance with the principle~ of the present invention, has an elongated hollow shank with two slots, one on each side. A pin block, having a hole communicating with both slots, is located within the elongated shank between first and second impact cushioning devices. A
~13~857 trailer can be attached to one end of the drawbar and a towing vehicle can be attached to the drawbar at the hole in the pin block between the two slot~ in the ~hank.
BRI~F DESCRIPTION OF T~E ~RAWI~G8 FIG. 1 is a side view of a preferred energy dampening drawbar.
FIG. 2 is a cross sectional view taken on the line 2-2 in FIG. 1 FIG. 3 is a cross sectional view taken on the line 3-3 in FIG. 1 FIG. 4 is a side view showing additional detail of an end bloc~
pin as used in the drawbar.
Other feature~, objects and advantages of the pre~ent invention will become more readily apparent from the following detailed description of the presently preferred embodiment, which i~
described in conjunction with above identified FIGURES of drawings which illustrate component parta a~ an aid to the description.
D~TAlT-~n DESCRIPTION OF T~E INVENTION
Referring to FIa. 1 and to F~a. 2 an energy da~r6n;ng drawbar, i~ identified, generally, by the numeral 10, and is illu~trated as ~134857 an aid to the following detailed description. An elongated shank 11 is constructed of square tubing 80 that it will fit into receiver types of hitches.
While ~quare tubing i9 preferred, for the reason identified above, the ~hank 11 can be formed from either round, rectangular, or polygonal stock when it is to be used with more specialized types of hitches.
The shank 11 has two elongated slots 12a and 12b located one on one side of the shank 11 and one slot on the opposite side. Only the one slot 12a is visible in FIG. 1 with the other slot 12b being present on the oppo~ite surface of the shank 11 and in alignment with the slot 12a.
A plate 13 is welded to one end of the shank 11. The opposite end of the shank 11 is open to provide for both assembly and maintenance access to the various component parts that are located inside the shank 11 of the drawbar 10.
The plate 13 has a hole 13a therein for accepting a hitch ball that is not shown in this view. A first cushion block 14 having a eize and ~hape eo that it will fit within the ehank 11 from the open end and rest against the ball plate 13. The ball plate 13 - 213~8~7 serves as a r~straint to prevent further movement of the first cushion block 14 within the shank 11 toward the ball plate 13.
A pin block 15 is contiguous with the first cushion block 14 and has a hole 16 in aligned with the elonqated slots 12a and 12b.
A second cushion block 17 having a size and shape to fit within the hollow shank 11 and is contiguous with the pin block 15.
A block 18 fits within the ~hank 11 and is contiguous with the second cushion block 17.
Referring to FIG. 3 and FIG. 4, the block 18 has a hole 19 extending through it. The shank 11 also has two holes 20a and 20b that align with the hole 19 when the block 18 is inserted in the shank 11.
A pin 21 through the holes 20a and 20b of the shank ll and through the hole 19 secures the block 18 in position within the shank 11. The block 18 is a restraint to prevent the second cushion block 17 from further movement within the shank 11.
The pin 21 is secured in position by a threaded set screw 22 that is threaded in the block 18. The ~et ~crew 22 i~ tightened until it bears against a recess 23 formed in the pin 21. The set ~1348~7 screw 22, after being firmly tightened, secures the block 18 in position within the hollow shank 11.
Since the purpose of the energy dampening drawbar 10 is to substantially eliminate shock impulses between the towing vehicle and the trailer, it is important that the component parts do not introduce additional slack that might aggravate the situation.
After assembly, a compressive force, such as is obtained from a press, i8 applied through the open end of the shank 11 against the block 18. The purpose of applying a compressive force is to remove any slack between the component parts- within the shank 11 and to also apply a slight compressive pre-load to the first and second cushion blocks 14 and 17. The amount of pre-load is selected according to the energy dampening characteristics desired for a particular drawbar 10.
The first cushion block 14 and the second cushion block 17 are constructed according to the energy dampening characteristics that are de~ired for a particular drawbar 10. The first and second cushion blocks 14 and 17, preferably are constructed of an elastomeric material, such as, for example, natural and synthetic rubber and urethane. The material that i~ ~elected must provide a desired resistance to compression.
~13~857 For example, the second cushion block 17 experiences all of the loading that is normally associated with towing a trailer and, as such, is usually under a considerable compressive load.
Therefore, the elastomeric material selected for the second cushion block 17 will have a higher durometer value than that selected for the first cushion block 14.
Certain special drawbar uses require exactly the opposite selection of properties for each of the cushion blocks 14 and 17.
The shape and size of each cushion block 14 and 17 also are varied to accommodate various types of material used in the construction of the shank 11 and, also, to vary the damp~ni ng characteristics for the drawbar 10. Each cushion block 14 and 17 is formed of a particular elastomeric material having a ~ize and shape to permit each cushion block 14 and 17 to be inserted into the hollow chamber formed by the shank 11.
For certain situations, a generally cylindrical shape is preferred to permit each cushion block 14 and 17 to deform during compression so as to accommodate the available space within a typical shank 11 having a square cross section. Each cushion block 14 snd 17 ie con~tructed, when required, to have a tapered end a~
shown in FIG. 1 and FIG. 2.
In certain situations, such as when it is desirable to obtain a progressive and variable dampening characteristic, the desired rate of dampening may not be obtAin~hle by the use of only one type of elastomeric material for each of the cushion block~ 14 and 17.
In such situations, each cushion block 14 and 17 is replaced by a plurality of cushion block~ on either side of the pin block 15.
When a plurality of cushion blocks are used, each block is selected to provide a particular desired dampening characteristic.
A modification to which the structure of the invention is adaptable permits the ela~tomeric material of either cushion block 14 and 17 to be replaced by a coil spring to provide the desired dampe~ing characteristics for certain specialized situations.
In another modification, the slots 12a and 12b, or the plug holes 20a and 20b are located elsewhere along the shank 11, or they are located on a different surface plane of the shank 11 tube as is required to ~atisfy use of the drawbar 10 with specialized types of hitche3, including certain types of wide ranging hitches.
Similarly, if desired, a separate restraint is affixed to the shank 11 and is used to prevent motion by the first cushion block 14, instead of relying upon the ball plate 13 to restrain the first cu~hion block 14.
~134857 -Operation:
In use, the drawbar 10 i8 in~erted into a receiver tube that is a part of the hitch mechanism of a towing vehicle, the shape of the receiver tube is similar, generally, to that of the elongated hollow shank 11. The interior dimensions of most receiver tubes are somewhat larger than the outside dimensions of the shank 11 to permit the shank 11 to be inserted quite readily into the receiver tube of a hitch mechanism.
When a conventional drawbar is used with many receiver tubes of today's hitches, a hitch pin is u~ed to secure the conventional drawbar within these receiver tubes. Normally, the hitch pin passes through a pair of holes that are provided in a receiver tube and, also, through corresponding holes in the conventional drawbar that align with the receiver tube holes.
However, when the energy dampening drawbar 10 of the present invention is used, the drawbar 10 is inserted into a receiver tube and a hitch pin is inserted through the holes in the receiver tube and through the slots 12a and 12b of the shank 11 and also through the hole 16 of the pin block 15.
Whon the dr~wbo.r 10 of th- invontion i- aon-truatod, th- hole 16 of the pin block 15 is within the opening of the slots 12a and ~134857 -12b. This permits the hole 16 to be aligned with holes in a receiver tube when the drawbar 10 i9 inserted. A hitch pin of any suitable type is inserted, and the drawbar 10 is secured within the receiver tube.
Should a failure of certain critical component part~ of the drawbar 10 occur, built-in safeguard~ en~ure that the drawbar 10 will not uncouple from the receiver tube. For example, if the end block pin 21 were to fail or to become dislodged from the block 18, the block 15 would be free to slide unimpeded longit~l~in~lly in a direction towards the open end of the shank 11. However, the hitch pin would eventually come into contact with one end of the two slots 12a and 12b, thereby preventing further travel by the block 15 and, thuæ, securing the drawbar 10 in the receiver tube during such a failure.
A hitch coupler on a trailer i~ connected to an appropriate hitch ball that normally passes through the hole 13a in the ball plate 13 to secure the trailer to the vehicle for towing.
When towing, the transfer of the force occurring between the towing vehicle and the trailer is eventually transmitted through the hitch coupling and to the eh~nk 11 of the drawbar 10. Ae the towing vehicle accelerates initially, the shank 11 is pulled in a ~13~857 direction gen~rally out of the receiver tube. The shank 11 is able to travel longitudinally within a maximum range of motion as determined by the length of the slot~ 12a and 12b. The block 15 is held stationary relative to the holes in a receiver tube by the hitch pin passing throuqh.
During acceleration, as the shank 11 is pulled slightly out from a receiver tube, the pin block 15 will bear against the second cushion block 17, which is compressed even further. The amount of the compression that is experienced by the second cushion block 17 is in proportion to the force applied by the towing vehicle and to the inertia of the trailer. A greater or lesser applied force will result in the greater or lesser proportional longitudinal motion of the shank 11 relative to the pin block 15.
The specific distance that the shank 11 actually moves relative to the pin block 15 for any given applied force is determined primarily by both the elastomeric and deformation properties of the second cushion block 17.
The act of compressing the second cushion block 17 reduces the severity of a jolt that would otherwise have been felt by occupants in the towing vehicle. During normal tranHit, the ~econd cu~hion block 17 will either relax or compress periodically in response to - ~1348~7 the exerted fQrces.
A similar process occur~ during deceleration of the towing vehicle, where the first cushion block 14 is compressed in proportion to the forces experienced. The functioning of the first cushion block 14 complements that of the second cushion block 17.
During transit, therefore, the first cushion block 14 will either relax or compress periodically in response to the exerted forces.
The compression and deformation of either of the cushion blocks 14 and 17 absorbs shock impulses and, later, returns the energy so absorbed during the subsequent relaxation and e~p~n~ion of either of the elastomeric cushion blocks 14 or 17. Shock impulses are decreased substantially by this action, and the ride as perceived by occupants is smoothed, and the wear and tear upon respective component parts is lessened also.
The invention has been shown, described and illustrated in substantial detail with reference to the presently preferred embodiment. It will be understood by those skilled in this art that other and further changes and modifications may be made without departing from the spirit and scope of the invention, which i8 defined by the claims appended hereto.
What is claimed is:
Claims (20)
1. An energy dampening drawbar for connecting a trailer to a towing vehicle, comprising:
means defining an elongated hollow shank of predetermined outer shape and size with an elongated inner chamber of predetermined dimensions with opposite ends and opposite sides, and including means defining a slot in said opposite sides;
block means located within said chamber, and having means defining a hole aligned with each of said slots in said opposite sides of said means defining said elongated hollow shank;
first resilient means located inside said inner chamber adjacent one of said ends for limiting longitudinal motion of said block means in a first direction;
second resilient means located inside said inner chamber adjacent the other of said ends for limiting longitudinal motion in a direction generally opposite said first direction; and means fixed at one of said opposite ends for, together with said hole in said block means and said slots, for attaching said elongated hollow shank between a trailer and a towing vehicle.
means defining an elongated hollow shank of predetermined outer shape and size with an elongated inner chamber of predetermined dimensions with opposite ends and opposite sides, and including means defining a slot in said opposite sides;
block means located within said chamber, and having means defining a hole aligned with each of said slots in said opposite sides of said means defining said elongated hollow shank;
first resilient means located inside said inner chamber adjacent one of said ends for limiting longitudinal motion of said block means in a first direction;
second resilient means located inside said inner chamber adjacent the other of said ends for limiting longitudinal motion in a direction generally opposite said first direction; and means fixed at one of said opposite ends for, together with said hole in said block means and said slots, for attaching said elongated hollow shank between a trailer and a towing vehicle.
2. An energy dampening drawbar as defined by claim 1 wherein said first and said second resilient means are blocks of a predetermined resilient material.
3. An energy dampening drawbar as defined by claim 1 wherein said first and said second resilient means are spring means.
4. An energy dampening drawbar as defined by claim 1 wherein said first resilient means is a block of a predetermined resilient material, and said second resilient means is a spring means.
5. An energy dampening drawbar as defined by claim 1 wherein said first resilient means is a spring means, and said second resilient means is a block of a predetermined resilient material.
6. An energy dampening drawbar, comprising:
an elongated hollow shank of a predetermined shape and size having two co-axial parallel slots formed therein on opposite sides;
a first restraint means attached to said shank;
a second restraint means attached to said shank;
a first cushion means having a predetermined shape and size located inside said shank adjacent said first restraint means for limiting the longitudinal motion in a first direction of said first cushion means within said shank;
a second cushion means having a predetermined shape and size located inside said shank adjacent said second restraint means for limiting the longitudinal motion in a second direction that is generally opposite to said first direction of said second cushion means within said shank;
and a pin block means having a hole therethrough located inside said shank and having said first cushion means situated adjacent a first side of said pin block means and having said second cushion means situated adjacent a second side of said pin block means that is generally opposite to said first side and having said hole align with a portion of said two co-axial parallel slots formed in said shank.
an elongated hollow shank of a predetermined shape and size having two co-axial parallel slots formed therein on opposite sides;
a first restraint means attached to said shank;
a second restraint means attached to said shank;
a first cushion means having a predetermined shape and size located inside said shank adjacent said first restraint means for limiting the longitudinal motion in a first direction of said first cushion means within said shank;
a second cushion means having a predetermined shape and size located inside said shank adjacent said second restraint means for limiting the longitudinal motion in a second direction that is generally opposite to said first direction of said second cushion means within said shank;
and a pin block means having a hole therethrough located inside said shank and having said first cushion means situated adjacent a first side of said pin block means and having said second cushion means situated adjacent a second side of said pin block means that is generally opposite to said first side and having said hole align with a portion of said two co-axial parallel slots formed in said shank.
7. An energy dampening drawbar as defined by claim 6 wherein said first restraint means includes a ball plate means extending from said shank for attachment of a trailer coupling apparatus thereto.
8. An energy dampening drawbar as defined by claim 6 wherein said first cushion means includes elastomeric means.
9. An energy dampening drawbar as defined by claim 8 wherein said elastomeric means includes urethane means.
10. An energy dampening drawbar as defined by claim 8 wherein said elastomeric means includes rubber means.
11. An energy dampening drawbar as defined by claim 6 wherein said first cushion means includes spring means.
12. An energy dampening drawbar as defined by claim 6 wherein said first cushion means includes a plurality of first cushion means.
13. An energy dampening drawbar as defined by claim 6 wherein said second cushion means includes elastomeric means.
14. An energy dampening drawbar as defined by claim 13 wherein said elastomeric means includes urethane means.
15. An energy dampening drawbar as defined by claim 13 wherein said elastomeric means includes rubber means.
16. An energy dampening drawbar as defined by claim 6 wherein said second cushion means includes spring means.
17. An energy dampening drawbar as defined by claim 6 wherein said second cushion means includes a plurality of second cushion means.
18. An energy dampening drawbar as defined by claim 6 wherein said shank is open at one end thereof.
19. An energy dampening drawbar as defined by claim 6 wherein said second restraint means includes end block means.
20. An energy dampening drawbar as defined by claim 19 wherein said end block means includes means to secure said end block means in a predetermined position within said shank.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002134857A CA2134857C (en) | 1994-11-01 | 1994-11-01 | Energy dampening drawbar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002134857A CA2134857C (en) | 1994-11-01 | 1994-11-01 | Energy dampening drawbar |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2134857A1 CA2134857A1 (en) | 1996-05-02 |
| CA2134857C true CA2134857C (en) | 1997-08-05 |
Family
ID=4154576
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002134857A Expired - Lifetime CA2134857C (en) | 1994-11-01 | 1994-11-01 | Energy dampening drawbar |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2134857C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108621718B (en) * | 2018-06-26 | 2023-10-20 | 河南森源电气股份有限公司 | Trailer traction connection device and transfer trolley |
-
1994
- 1994-11-01 CA CA002134857A patent/CA2134857C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2134857A1 (en) | 1996-05-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20141103 |