Weight distribution hitch with angled moment bar for pre-load adjustment
A weight distribution hitch system comprising a vehicle attachment member comprising a forward end configured to rigidly attach to a vehicle, and a rearward end extending rearwardly toward a trailer, the rearward end comprising an upper portion comprising a trailer attachment member configured to pivotally attach to a coupler of the trailer, and a lower portion configured to receive a moment bar; a tension member comprising a top end configured to be supported by a frame member of the trailer, and a bottom end, and a moment bar, the moment bar comprising a first end configured to either be attached the lower portion of the rearward end of the vehicle attachment member or to be supported by the bottom end of the tension member, a second end also configured to either be attached to the lower portion of the rearward end of the vehicle attachment member or to be supported by the bottom end of the tension member, a first major face configured to face either generally upward or generally downward, a second major face opposite the first major face and also configured to face either generally upward or generally downward, and a bend between the first end and the second end; wherein, when the tension member is in tension, it imposes an upward force on the end of the moment bar that is supported by the tension member, which, in turn, imposes a forward moment on the vehicle; and wherein a preload on the moment bar is varied depending on whether the first major face faces generally upward or generally downward is disclosed.
1. A weight distribution hitch system, comprising:
a vehicle attachment member comprising:
a forward end configured to rigidly attach to a vehicle, and
a rearward end extending rearwardly toward a trailer, the rearward end comprising:
an upper portion comprising a trailer attachment member configured to pivotally attach to a coupler of the trailer, and
a lower portion configured to receive a moment bar;
a tension member comprising:
a top end configured to be supported by a frame member of the trailer, and
a bottom end, and
a moment bar, the moment bar comprising:
a first end configured to either be attached the lower portion of the rearward end of the vehicle attachment member or to be supported by the bottom end of the tension member,
a second end also configured to either be attached to the lower portion of the rearward end of the vehicle attachment member or to be supported by the bottom end of the tension member,
a first major face configured to face either generally upward or generally downward,
a second major face opposite the first major face and also configured to face either generally upward or generally downward, and
a bend between the first end and the second end;
wherein, when the tension member is in tension, it imposes an upward force on the end of the moment bar that is supported by the tension member, which, in turn, imposes a forward moment on the vehicle; and
wherein a preload on the moment bar is varied depending on whether the first major face faces generally upward or generally downward.
2. The system of claim 1 , wherein the bend is closer to the first end than the second end and wherein the preload on the moment bar is also varied depending on whether the first end or the second end of the moment bar is attached to the lower portion of the rearward end of the vehicle attachment member.
3. The system of claim 1 , wherein a jack pre-loads the bar.
4. The system of claim 3 , wherein the jack comprises a laterally extending bearing member extending from at or near the bottom of the jack and configured to abut the bottom surface of the moment bar with enough force to lift the moment bar until enough of a forward moment is imposed on the vehicle to overcome a rearward moment imposed on the vehicle from a tongue of the trailer.
5. The system of claim 1 , further comprising a second moment bar.
6. The system of claim 1 , further comprising a lifting mechanism configured to lift the rearward end of the moment bar to a point where the tension member can engage the moment bar.
7. The system of claim 1 , wherein the tension member comprises a hinge configured to allow the tension member to swing from a first position to a second position.
8. The system of claim 1 , wherein the moment bar connects to the lower portion of the attachment member via a barrel coupling comprising an inner cylinder and an outer cylinder.
9. The system of claim 1 , wherein the modulus of elasticity of the moment bar is less than 10,000 ksi.
10. The system of claim 1 , further comprising a metal endcap to protect the moment bar from high point stresses, the metal endcap comprising a forward end and a rearward end, the forward end configured to receive and fix to the moment bar and the rearward end configured to abut the tension mechanism such that the upward force from the tension mechanism translates to the moment bar.
11. The system of claim 10 , wherein the metal endcap is removable.
12. The system of claim 1 , wherein the moment bar has a modulus of elasticity less than 15,000 ksi.
13. The system of claim 1 , wherein the moment bar has a modulus of elasticity less than 14,000 ksi.
14. The system of claim 1 , wherein the moment bar has a modulus of elasticity less than 13,000 ksi.
15. The system of claim 1 , wherein the moment bar has spring constant less than 1,000 lbs/inch.
16. The system of claim 1 , wherein the moment bar has spring constant less than 900 lbs/inch.
17. The system of claim 1 , wherein the moment bar has spring constant less than 800 lbs/inch.