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  1. #11
    Gold Member uhmgawa's Avatar
    Join Date
    May 2003
    Posts
    282
    Location
    New Hampshire
    Tractor
    Kubota L48TLB

    Default Re: Loader chain hooks

    </font><font color="blue" class="small">( Hmmm...
    Interesting observation...
    Could you eloborate more on your statement, please?

    &gt; Doing so the bucket can be driven against its roll-back mechanical
    &gt; stop thus preventing reverse stress loading of the hydraulics.

    Especially the "reverse stress loading of the hydraulics"?
    )</font>

    The torque of the tractor applied to a hydraulic
    cylinder can exceed the design pressure of the system.
    This is particularly true of impact loads where the
    pressure relief valve may not be able to vent
    sufficient fluid volume quickly enough to protect
    system components.

    A safer approach when pulling/pushing with a
    loader bucket where the generated force is applied
    rotationally to the bucket (eg: via chain) is to rotate
    the bucket to either of its mechanical stops. Doing so
    the force applied is seen by the mechanical stop rather
    than transmitted to a hydraulic cylinder.

    The above scenario is similar to the caution against
    applying full horizontal torque of the tractor to a
    bucket edge situated at a vertical 90*.

  2. #12
    Gold Member uhmgawa's Avatar
    Join Date
    May 2003
    Posts
    282
    Location
    New Hampshire
    Tractor
    Kubota L48TLB

    Default Re: Loader chain hooks

    </font><font color="blue" class="small">( Sorry Uhmgawa,

    But you lost me a bit too, I have read and re-read your explanation...

    And understand your "reverse stress loading" statement. Although when working a setup like Flusher's example the bucket is useful to provide vertical alignment/support of the sample lift.)</font>

    That scenario isn't as much of a concern as the load is
    fixed and not impact-applied. Ie: you either lift the load
    or the relief valve vents. In this case the loader/hydraulic
    system is able to protect itself per design.

    As a contrived example to the contrary for the same scenario,
    if you were to strike the bottom of the wall on the foundation
    while the tractor was traveling horizontally you could
    impact load the hydraulic system beyond its design limit.

    </font><font color="blue" class="small">( But, why would 4WD CG be different than 2WD?)</font>

    Operating in 4WD the front axle can generate sufficient
    torque to lift the rear end of the tractor. This is also the
    reason chains should be routed around the back of a loader
    bucket and exit under the bucket, with the bucket positioned
    as low as possible. Attaching a chain directly to the top of a
    bucket creates greater mechanical advantage to lift the rear
    end as well as the ability to do so by increasing traction of the
    front tires. Chains routed via the bucket bottom are also
    marginally safer in the case of breakage.

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