초록 ▼

A damped drawbar for use in towing a drawn trailer that provides for the attenuation of noise, shock, and vibration that may be conducted into the towing vehicle. The newly designed drawbar uses a resilient elastomer, operating in shear, sandwiched between an outer steel tube and an inner steel tube

A damped drawbar for use in towing a drawn trailer that provides for the attenuation of noise, shock, and vibration that may be conducted into the towing vehicle. The newly designed drawbar uses a resilient elastomer, operating in shear, sandwiched between an outer steel tube and an inner steel tube, to reduce noise by damping the undesirable vibrations. A cushioned hitch pin coacting with the ovate holes in the inner tube, reduces the noise from a jolt caused by the hitch pin over-travel, during acceleration or deceleration, by as much as 95 percent. The hitch pin coacting with the ovate holes in the inner tube, serves as a mechanical fail-safe should the towed member be grossly beyond the drawbar's rated load capacity.

대표청구항 ▼

1. A drawbar for a tow hitch, comprising:an inner housing and an outer housing with a longitudinally mounted elastomeric member therebetween, the elastomeric member comprising a resilient linear damping element communicating with both the inner and the outer housing with a resistance to omnidirectio

1. A drawbar for a tow hitch, comprising:an inner housing and an outer housing with a longitudinally mounted elastomeric member therebetween, the elastomeric member comprising a resilient linear damping element communicating with both the inner and the outer housing with a resistance to omnidirectional forces applied to the drawbar from a towing vehicle or a drawn load;the inner and outer housing each having a pair of coincident cross holes;wherein each of the cross holes of the inner housing are larger than the corresponding cross holes of the outer housing. 2. A drawbar for a tow hitch according to claim 1, the hitch including a hitch pin for insertion in the through slots and displaced orthogonal to a longitudinal axis of said inner and said outer housing. 3. A drawbar for a tow hitch according to claim 2, wherein the elastomeric member surrounds the inner housing. 4. A drawbar for a tow hitch according to claim 3, wherein a forward end of the inner housing extends forward beyond the surrounding elastomeric member. 5. A drawbar for a tow hitch according to claim 4, wherein each of the inner housing cross holes are ovately shaped with a minor vertical axis and a major horizontal axis, thereby allowing sufficient clearance from the hitch pin in the minor vertical axis and the major horizontal axis to permit vertical and horizontal motions without contacting the hitch pin during normal use. 6. A drawbar for a tow hitch according to claim 5, wherein the hitch pin includes a coating of an elastomeric material that provides an elastomerically cushioned hinge pin to further attenuate transmission of shock, noise, bounce and vibration between a tow vehicle and a towed load. 7. A drawbar for a tow hitch according to claim 6, further comprising an outboard end of the inner housing that extends beyond an outboard end of the outer housing and wherein the inner housing is welded to a trailer connection. 8. A drawbar for a tow hitch according to claim 7, the outer housing and the inner housing each having a square shape. 9. A drawbar for a tow hitch according to claim 7, the outer housing and the inner housing each having a cylindrical tube shape. 10. A drawbar for a tow hitch according to claim 1, the outer housing and the inner housing each comprising a low carbon steel that has the mechanical strength to withstand a hoop stress and additional forces occurring in all directions placed thereupon by the elastomeric member and a hitch receiver of the tow vehicle. 11. A drawbar for a tow hitch according to claim 10, wherein the low carbon steel square outer housing fits over a receiver tube of the tow vehicle. 12. A drawbar for a tow hitch according to claim 1, the elastomeric member including a plurality of high hysteresis elastomer sleeves that are compressed and contained between the inner housing and outer housing to provide total isolation from noise or vibration that may be conducted from one housing to the other during typical operation and to dampen forces imposed upon the tow vehicle by an inertia of the towed load. 13. A drawbar for a tow hitch according to claim 12, wherein the elastomeric member comprises a natural rubber that is vulcanized, and bonded to an inner metal surface of the outer housing and an outer metal surface of the inner housing. 14. A drawbar for a tow hitch according to claim 12, wherein the elastomeric member is comprised of a synthetic rubber that is chemically bonded to an inner metal surface of the outer housing and an outer metal surface of the inner housing. 15. An elastomerically isolated tow hitch drawbar comprising:a square inner tube welded to a bracket of a towed load, the inner tube displaced within a square outer tube with at least one elastomeric sleeve compressed between the inner and the outer tube to provide total isolation from noise or vibration that may be conducted from one tube to the other;the inner tube having ovately shaped cross holes on both sides, wherein a horizontal diameter of each of the holes is larger than a vertical diameter thereof, and wherein, the inner tube cross holes are coincident with circular cross holes of the outer tube;wherein the outer tube is slidably insertable into standard a receiver tube of a towing vehicle, the receiver tube including cross holes on both sides, with a hitch pin insertable through the tube holes to secure the towed load to a low vehicle provides a clamp to absorb any play between the receiver tube and the drawbar tubes and to direct all of the shock, noise, bounce and vibration that are typically related when towing through the at least one elastomeric sleeve. 16. An elastomerically isolated tow hitch drawbar comprising:an outer tube welded to a bracket of a towed load having an inner tube displaced within the outer tube with at least one elastomeric sleeve compressed between the inner, and the outer tubes to provide total isolation from noise or vibration that may be conducted from one tube to the other;wherein a forward end of the inner tube extends beyond and projects from a forward end of the outer tube, the inner tube having ovately shaped cross holes on both sides, which are coincident with circular cross holes of the outer tube to receive a clamp inserted in the tube holes to retain the inner tube within the outer tube;the inner tube including cross holes on each side near its forward end; and, the inner tube slidably insertable into a receiver tube of a towing vehicle, the receiver tube including cross holes on both sides to receive a hitch pin insertable through the inner tube and receiver tube holes to secure the towed load to the tow vehicle, wherein the clamp absorbs any play between the receiver tube and the drawbar tubes and directs all of the shock, noise, bounce and vibration that are typically related when towing through the at least one elastomeric sleeve. 17. An elastomerically isolated tow hitch drawbar according to claim 16, wherein the at least one elastomeric sleeve is compressed between the inner and the outer tubes, provides a maximum surface area of elastomeric material in a linear arrangement between the tubes, and comprises in a shear mode of operation a reduced shearing stress, wherein the shearing stress equals an applied longitudinal force divided by a surface area of the elastomeric material.