pin is ‘seized’. After a bit of persuasion with a 14lb hammer, we then reach for the oxy-acetylene and bits of the machine are burned and chopped off. Rest-assured, it’s never the same again.
What’s to be done?
The traditional fix for medium and large plant was line boring, where the component is removed - e.g. the boom, its fixed bores welded up and then a portable boring tool is used to re-engineer the hole. It’s not a quick or cheap fix, and even where it’s just bored out and sleeved there are lots of additional challenges, the most basic being that this kit only tends to suit bores of 50mm diameter or more. That rules out mini diggers straight away.
Fitting the pin is straightforward with the ability to take out up to 2mm movement as standard, but any size hole can be accommodated with up to 1.5mm ovality, i.e. you might have to dress the bore with a flapwheel to even the wear out. The pins come with clear instructions for fitting and removal should you need to take the machine apart again.
Choosing the right pin is simple.
Line boring equipment in use on a crane boom cylinder pivot.
The other option is where the re-engineering is done for you. The Expander System from Nord‑Lock Group is one of those options. Its not new to the market but is rarely used on smaller kit as most firms often didn’t know the option existed. In my early days on the tools, these were a standard fit from new on highly stressed pivots and were a fit and forget item. 10,000 hours in and the pivot lugs would still be like new hence Nord-Lock Group offer a 10,000 hour lug wear warranty on their products.
Installation of the Expander pin at the boom to dipper pivot - movement fixed forever. Costs and conclusion
Each pin assembly is simply priced, the more complex the pin the higher the cost - for example, an Expander System boom pin for a Kubota U10-3 is £175. This makes for easy maths if compared to all the costs of other repair options.
You could opt for kingpost removal and replacement which is do-able but not quick. You will end up with a machine likely to be out of the available hire fleet for at least a week. Worst still a new kingpost is serious money. Used ones on auction sites fetch £350 or more and, as it’s used, it will no doubt have similar movement. Instead you buy the Expander System pins you need and replace them during routine service and inspection. Happy days.
A simple fix - the tapers do the work.
Getting the right pin is easy, you can order based on the machine model and position or get a bespoke pin. The beauty of this is once a new pin need is identified, that is then on their system. Expander offers engineered pins for diameters of 10mm or larger and cater for blind bores, flush mountings and a range of other fitments to suit equipment.
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I would look at what you have done in the past and then price up this alternative, if you fit them on your new kit in all the prone places, they will be as tight at the end of their time with you as they day you fitted them. Why not have a wander in your yard and if you run 1 tonne hi-tip dumpers, with the engine off, move the steering wheel to and fro, and just look at how much play there is in the steering ram pivots. They have generous clearance from new - imagine that in 1,000 hours or so!
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