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2012Oudoorsman's avatar
2012Oudoorsman
Explorer
Aug 01, 2013

Equalizer Hitch Question

I was able to set up the hitch perfectly to where it restores 360 of 400lbs from front axle and the truck and trailer ride great now. My question deals with the friction point of the L bracket and bar.

The L bracket has approx a 2 sq. in. area that the bar rests on and creates friction to stop the trailer from swaying. I noticed a couple months ago that the L bracket was not making a lot of contact with the bar and the point of contact was shaped like a C and was on only on 3 sides and approx an 1/8" thick. Needless to say it wasn't contacting the full surface or even half. Thinking that the edges were a little high a lightly filed what I though were the highspots so the bar would contact the whole surface area. Now the bar only makes contact on the side that the L bracket is bent. This friction point is about 1/8" thick still by about an inch long. So I feel I can increase the friction greatly if I find out how to increase the contact surface area. I feel if the L bracket was bent more it would make contact along the entire surface and create more sway resistance.

Has anyone else experienced this issue. I do plan on contacting equalizer but was looking to see if anyone else had the same issue as it seems like a very popular hitch.

I'm not sure if this would help by my equalizer has 1200lbs bars and I have a 900lbs per scale tongue weight.

Any input would be appreciated, Thanks.
  • 2012Oudoorsman's avatar
    2012Oudoorsman
    Explorer
    Aug 02, 2013
    http://m.dummies.com/how-to/content/how-surface-area-affects-the-force-of-friction.html

    This kinda explains it a simpler as the friction stays the same bc the force decreases when area increases. Personally I would rather have the increases surface area. But I guess my original assumption of higher friction is incorrect
  • Campin_LI's avatar
    Campin_LI
    Explorer
    Aug 02, 2013
    Only my opinion: Don't put too much faith into the sway control aspect of these hitches, including Reese. I think a lot of marketing makes it appear to be more effective. Yes, friction exists, but is that friction more or less negligible compared to the forces produced by a swaying trailer? Maybe. I'm sure that heavier and longer trailers produce greater forces than shorter, lighter trailers.

    I have the Equal-i-zer hitch. Assuming you have the L-bracket set at the maximum distance from the hitch ball, try moving the L-bracket a little closer to the ball to see if the bar seats a little better.

    On edit: Based on the angle of your hitch head, as you turn (or as the trailer sways - hopefully never) and depending on the terrain, those stiff bars are going to rotate on the L-bracket.
  • TomG2's avatar
    TomG2
    Explorer
    Aug 02, 2013
    The catch is that the wear would be accelerated with the lower contact area. Think of is a knife on a block of wood. A knife edge will cut through the wood much faster than would a flat piece of steel. One half square inch of contact area will wear much faster that a full square inch, even though the sliding force involved may be equal.
  • Ron_Gratz's avatar
    Ron_Gratz
    Explorer
    Aug 02, 2013
    2012Oudoorsman wrote:
    ---Either way it works good but I feel that an increase in the surface area could make it function great now and during the windy/nasty days.
    Based on all I've read, I feel that an increase in the contact area would not result in any significant increase in friction force between bar and L-bracket.

    I've done a lot of searching for reports of steel-on-steel coefficients of friction which are dependent on contact area. I've found none. I'm aware that absence of evidence is not evidence of absence, but there should be data available for a friction/area dependency if it does exist.

    I did find the following which, IMO, gives a good explanation of why there should be no significant dependency:

    Because surfaces aren't smooth on the atomic scale, when you touch two surfaces together only the high points (asperities) on the surfaces make contact so the real area of contact is much smaller than the apparent area of contact.

    The reason why the force is approximately independent of area is that as you increase the force you get elastic deformation of the asperities and the real area of contact per asperity increases. If you increase the area you increase the number of points of contact but you also decrease the force per point of contact so the asperities deform less and the real area of contact per asperity goes down.

    The real area per asperity is roughly proportional to pressure, i.e. F/A , and the number of asperties in contact is proportional to area A . So when you multiply these together you find the real area of contact, and hence the friction, is just proportional to the applied force.

    For relatively soft materials like rubber the approximation doesn't hold, and their frictional behaviour is a lot more complex.



    Ron
  • 2012Oudoorsman's avatar
    2012Oudoorsman
    Explorer
    Aug 02, 2013
    rightyouareken wrote:
    I don't recall what the wear pattern looks like on my L brackets, but I have noticed that the wear pattern on my bars seems to be improving with mileage. They were wearing mostly on one side of the bar when new and are now wearing more evenly across the bar. Think hitch head angle probably affects this to some minor degree as the bars when hooked are slightly off from the axis of tilt, meaning the inside edges of the bars would be very slightly lower than the outside if I'm not mistaken, due to head tilt and the fact that they are at a less than 90 degree angle from the axis of tilt of the head. Also check and make sure your l bracket resting surface is parallel with the bars front to back.

    I haven't really been motivated to look into it because it tows ok, but I'm sure you're right that performance may be improved with more even contact between the bars and brackets.


    My bars are very close to be parallel. I do have the L brackets angled slightly so the bar rests on them parallel and not at different angles as you mentioned. I do not have many miles and maybe with more use they will wear in as you mentioned. Either way it works good but I feel that an increase in the surface area could make it function great now and during the windy/nasty days.
  • rightyouareken's avatar
    rightyouareken
    Explorer
    Aug 01, 2013
    I don't recall what the wear pattern looks like on my L brackets, but I have noticed that the wear pattern on my bars seems to be improving with mileage. They were wearing mostly on one side of the bar when new and are now wearing more evenly across the bar. Think hitch head angle probably affects this to some minor degree as the bars when hooked are slightly off from the axis of tilt, meaning the inside edges of the bars would be very slightly lower than the outside if I'm not mistaken, due to head tilt and the fact that they are at a less than 90 degree angle from the axis of tilt of the head. Also check and make sure your l bracket resting surface is parallel with the bars front to back.

    I haven't really been motivated to look into it because it tows ok, but I'm sure you're right that performance may be improved with more even contact between the bars and brackets.
  • 2012Oudoorsman's avatar
    2012Oudoorsman
    Explorer
    Aug 01, 2013
    Ron,

    I understand the surface area and how it affects friction, I am actually a Mechanical Engineer and took all those classes. I also do understand that a lot of the friction is generated at the socket head, infact I think per Equalizers wording more than 50% is generated at the socket head. However its this remaining portion I feel that I'm not using to its full advantage.

    I have been super lucky so far, knock on wood, that the days i've traveled have been sunny and no wind but I know my luck is running out. So i figured if I could help increase this friction it would greatly help me on these windy days or days that there seem to be many tractor trailers flying by.

    I do appreciate your insight as i've yet to see you post something that was not helpful or insightful. Have you seen or heard what i'm talking about though?

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