Valuable Error Piece!

[Idris]

I don't know how many members were following Nick's spare wheel 20a on Ebay which finished yesterday evening. I most certainly was, because I was interested to find out whether I'd paid ovbert the odds for my example.
As it was, it turned out that I got mine cheap, Nick's example selling for a whopping £218!
Not a bad price for an error piece, was it?

[motorman]

I am not an expert in RW's but can someone please explain how this is an error piece?

The spare wheel was clearly designed to be there on this variant, so how can it be considered an error?...............am i missing something?

[fixer]

from what I understand Alex it's an extra wheel that gets stuck behind the cab when the casting gets tumbled and then painted ,looks like it should always be there though (someone please correct me if I'm wrong)

[Idris]

from what I understand Alex it's an extra wheel that gets stuck behind the cab when the casting gets tumbled and then painted ,looks like it should always be there though (someone please correct me if I'm wrong)

That's what people say. The wheels and bodies are said to have been tumbled together initially (later on, it was done separately) and, quite by chance, the distance between the back of the cab and the backboard was just right for wheels to lodge in there. hence the error piece designation.
I also agree that it very much looks the part, which is why I went to great lengths (and waited thirty years) to add one to my collection.

[motorman]

from what I understand Alex it's an extra wheel that gets stuck behind the cab when the casting gets tumbled and then painted ,looks like it should always be there though (someone please correct me if I'm wrong)

That's what people say. The wheels and bodies are said to have been tumbled together initially (later on, it was done separately) and, quite by chance, the distance between the back of the cab and the backboard was just right for wheels to lodge in there. hence the error piece designation.
I also agree that it very much looks the part, which is why I went to great lengths (and waited thirty years) to add one to my collection.

This tumbling that you refer to? can you clarify in what stage of the maufacturing process this takes place and what the purpose of tumbling the wheels and bodies together was? This is an excellent explanation for the "error" occuring. I would just like to know why it was neccesary to have both these parts tumbling together?

Apologies for the further questions but i find this quite interesting.

[Idris]

My understanding is as follows: when items are diecast, there are channels which are used to lead the molten metal to, and also release air from the actual mould. When the casting is released, most of the metal which has solidified in the channels can be easily removed. However, there will always be small tails left on the casting, disfiguring it plus areas of flash (caused by molten metal leaking into thin gaps between the individual sections of the mould). If the castings are then quite literally tumbled together (either with or without some kind of abrasive), these weak tails are worn down and break off, leaving clean castings behind.
In some cases, such as the one in question, it can have unintended consequences. Other examples are the open ladder on the 65c Combine which was apparently prone to deformation during tumbling, hence it almost immediately being filled in. I have also heard that a similar problem with the 34c VW Camper resulted in the decision to lower the roof.

[motorman]

Thanks Hugh, i thought that the tumbling process you referred to may have been something to do with cleaning up the rough edges/spurs left after the intial casting was done.

Is it possible also that the factory workers saw the attraction of some of these error peices especially something like the 20a Nick sold and deliberately made them to supply to the few enthusiasts/collectors clubs that were around at the time, who may have even asked for some of these error pieces to be made on their behalf?

[Idris]

Whilst it's a;ways possible that the 20a spare wheel variation was made deliberately, this does seem unlikely because the wheel has been painted together with the body casting. (How many maroon tyres do you see as you go about your daily business?)

[SMS88]

This variation strikes me as so unusual because I am amazed that Lesney tumbled wheels at the same time as 20a body castings - for production assembly purposes different castings could logically be kept separate to save the cost of having to separate them out - from metal wheel mould numbers we can be sure that the wheels were NOT cast on a sprue with the bodies and baseplates.Getting accidentally wedged into the crack behind the cab is a much longer shot than wheels being deliberately put there - a number of 1-75 series had spare tyres so we cannot completely rule out that it wasnt an idea like windows in 23cs - perhaps the very earliest production run had the wheel deliberately added, in no way an error.Indeed we all know that the brace behind the cab was a casting MODIFICATION - it is actually very credible to me that Lesney probably tried the spare tyre behind the cab as either an alternative to the added brace or as an addition to the brace!

The 23a-b &c are examples of castings which were partially assembled BEFORE painting so its not an unprecedented detail to add! However if the tyres on the handful of examples known are from random other 1-75 series rather than all the same that would enhance the error theory -all the same would support it being planned most likely as trial assembly before mass production began again like glazed or maroon baseplate 23cs. Paint being needed to ensure the spare tyre stayed wedged in place!

[Idris]

Mick makes some interesting points, but I think another argument against it being deliberate is that, in real life, you wouldn't fit the spare wheel between the cab and the backboard since it would be extremely difficult to get it up/down. I may be wrong, but I think 1950s lorry spares were normally stored horizontally, suspended from the chassis either between the two axles or to the rear of the rear axle.
Furthermore, having found the model without brace to be too weak to stand up to playwear (we know this from the pale green versions that have been found), it seems odd that Lesney would add a brace and a spare wheel, especially since the latter would cost money.
Although it very much looks the part and much as I would like to believe that it is a deliberate variation, I think that odds are that the acceped position on these is correct: it is merely an error piece caused by tumbling wheel and body castings together.