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Crane Knee Joints or Track Supports.

Crane knee joints for overhead cranes rails to run on. What is a Knee joint, And How Does It Work?

Many clients like to attach their overhead crane to the building, to maximize the width of travel. Most weeks people ask us “can I attach an overhead crane to my building via crane knee joints?”

In essence the knee joint supports the crane rails, at each end of it. a gantry rail sits on top of the knee joint, and the rails run at 90 degrees to it. The knee joint itself is bolted to the building, or occasionally welded. When supporting or attaching an overhead cranes structure to a building you have 2 choices. You can ask their structural engineers to supply and fit them, or your chosen gantry crane supplier can do it. Crane knee joints are also called knee brackets, joints or stubs. In essence, your crane’s rails or steelwork will need supporting in the air.

Knee joints.

Crane knee joints, pictured below, are fastened the building upright column. This saves money, as they do not need crane free standing column steelwork bolting to the floor as well, and work especially well with new buildings.

Some factories will have knee joints already fastened to them prior to the crane being delivered, or even rails in situ. Alternatively you can ask your steel erectors (builders) to include knee joints when the factory is being built. Prior to this please ensure your structural engineers have asked for the crane weights, overturning moments and the forces imposed by the overhead gantry crane, its self-weight and the load it is carrying.

All reputable EOT crane companies can supply these. All that we ask is that your installation guys make sure the knee joints are level, laterally, longitudinally and height wise. Oh and please leave enough room above the knee brackets for the rails to run on and also the crane and its end carriages.

We will always offer to work with your chosen civil engineers, architects, and pre-construction team. The most common crane knee joint question is, “what height is required from the rail to building’s eaves?”

crane knee joints

crane knee joints

Crane knee joints

Remember to check.
If we are landing our crane onto your free issue rails, please ensure prior to delivery of the new crane:
  • Your installation team to leave enough room above the knee bracket for the down shop tracks, AND the crane beam AND the cranes end carriages.
  • You leave a minimum of 200-250mm between the building uprights to the centre line of the crane rails, so we can lift, turn (spin) and land the crane.
  • Please don’t forget to fit, and weld the sold bar, or rail on top of the I-beams. The crane does not run on the universal beam, it runs on the solid bar welded to it. Please use a 50×50 solid bar S355 grade.
  • Please ensure the crane rails are level and parallel in both directions.
  • That the solid bar used will narrow enough, moreover will they take the cranes end carriage wheels?
  • Lastly please ensure the span of the rails are parallel and within plus or minus 2-3mm tolerance.



mitered crane rail

Crane rails joints do not need to be welded if they have a mitered rail on top


If any of the checks above are not carried out correctly the crane installation will be aborted. Alternatively, we can take this headache away for you, by supplying and installing your crane steelwork to British standard. It’s what we do most weeks.

crane solid bar

If this page has been helpful and you would like to learn a little more about crane steelwork, rail or solid bar, click here. Also please visit our frequently asked overhead traveling crane questions page.

If you didn’t find what you require on this page please visit our frequently asked questions crane page. Lastly, visit our overhead crane YouTube channel.