Daimler Bus Replica King-pin Repairs...

Daimler Bus Replica King-pin Repairs…

The Museum’s bus fleet is formed of three vehicles at present – two very good replicas plus one accessible bus.  Of the two replicas, the ‘D’ bus (based on a 1913 Daimler used by Gateshead Tramways, later Northern General) has been in continuous operation at Beamish for nearly 30 years now.  At present it operates in Northern livery and sits upon its solid tyred wheels.  Pneumatics re available for winter operation though look appalling and are definitely not beneficial to its appearance!

With the summer holidays ahead and the need for as many vehicles in service as possible, the D was pulled in for re-bushing of the king-pins – a known weak area not least due to the effect of the unpaved or cobelled sections of route over which this vehicle operates.  So, it was planned that last week it would be brought into the workshop (following use on the Monday) and that Brian Williams and Chris Armstrong would set about re-bushing the king-pins and returning the bus to service in as few days as possible.  Sounds easy?  Not when there are no parts available off the shelf…  Here is a photo-sequence showing the work involved.

Work started on Tuesday, with the bus brought into the workshop, propped and the front wheels removed, followed by the brake drums and anything else obscuring the steering mechanism.

Below: Here is the front offside wheel, hub, drum and front axle. The king-pins enable the wheels to steer, and so must carry a variety of loads upon them.  The pins themselves are hardened, but the axle forging they fit into is not, and so is subject to wear that results in excessive slop in the steering and for the rotation of the wheels.

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Below: With the stripping well underway, the kingpin seen above (or not seen!) is exposed.  The pin is the shiny vertically aligned cylindrical shape, the forged axle spindle yoke being what it is located into.

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Below: With the pin removed, a reamer is used to open out the hole to enable bushing.  This is long (and lonely!) work, slowly working away the material to a pre-determined clearance in the enlarged hole.

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Below: Over in the machine shop, Chris began making the bushes.  These are very slender and a precise dimension both internally (into which the king-pin will locate) and externally (which is pressed into the front axle and the reamed holes).  These were machined on our Dean Smith & Grace (DSG) lathe.

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Below: The pin, with locating key, and the bush, with slot to clear the key on the pin.

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Below: The bush pressed into the axle.

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Below: The king-pin, fitted after being tidied up.  This includes a restored slot in the top to enable alignment of the keyway.

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Below: With pin reassembled, the brakes, drum and wheel are fitted up.  This is the offside, with the nearside receiving identical attention.  After inspection, testing and signing off, the bus returned to service, work complete.

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With thanks to Chris Armstrong for all of the photographs above and Andy Martin for the title photograph.