Class 33 - some questions

[darwins]

Firstly about the mass of the locomotives: The 1969 diagram book gives a class 33/0 as 73 tons 4 cwt and a class 33/2 as 74 tons 2cwt. The 1975 diagram book states 76 tons 9cwt and 76 tons 5cwt. Is there any explanation as to how the weight in working order apparently increased by 2 or 3 tons during that time? (Although at the same time fuel capacity is apparently reduced from 800 gallons to 750 gallons.

Secondly about the push-pull class 33/1 locos - when working with SR emu stock / TC sets they were able to operate the EP brakes on the mu stock and the vice-versa. Were they able to work in the same way as the mu stock by applying and releasing the EP brakes without reducing the pressure in the train brake pipe? Or did the train brake pipe pressure need to be reduced in order to operate the locomotive brakes in addition to the EP brakes being operated by electric circuits? Or did were the brakes simply operated as twin pipe air brakes without any electrical involvement?

 

[Magdalia]

Firstly about the mass of the locomotives: The 1969 diagram book gives a class 33/0 as 73 tons 4 cwt and a class 33/2 as 74 tons 2cwt. The 1975 diagram book states 76 tons 9cwt and 76 tons 5cwt. Is there any explanation as to how the weight in working order apparently increased by 2 or 3 tons during that time? (Although at the same time fuel capacity is apparently reduced from 800 gallons to 750 gallons.

Adding to rather than subtracting from the confusion, the 1965 diagram book has DE/3002/1 (standard loco) weighing 73 tons 8 cwt in working order and DE/3002/2 (Hastings Gauge loco) weighing 74 tons 4 cwt in working order, each with an 800 gallon fuel tank.

Ironically, "Slim Jim" weighs nearly a ton more than his brother! Is that the weight of slow speed control equipment which I think was only fitted to the Hastings Gauge locos?

You don't mention the weight of the push-pull locos. Obviously my 1965 source can reveal nothing about those.

 

[36270k]

Firstly about the mass of the locomotives: The 1969 diagram book gives a class 33/0 as 73 tons 4 cwt and a class 33/2 as 74 tons 2cwt. The 1975 diagram book states 76 tons 9cwt and 76 tons 5cwt. Is there any explanation as to how the weight in working order apparently increased by 2 or 3 tons during that time? (Although at the same time fuel capacity is apparently reduced from 800 gallons to 750 gallons.

Secondly about the push-pull class 33/1 locos - when working with SR emu stock / TC sets they were able to operate the EP brakes on the mu stock and the vice-versa. Were they able to work in the same way as the mu stock by applying and releasing the EP brakes without reducing the pressure in the train brake pipe? Or did the train brake pipe pressure need to be reduced in order to operate the locomotive brakes in addition to the EP brakes being operated by electric circuits? Or did were the brakes simply operated as twin pipe air brakes without any electrical involvement?

The Class 33/1 was not fitted with EP brakes.
When working with TC or EMU stock the westinghouse brake would be used. ie by controlling the brake pipe pressure. This would apply when driving from the Class 33/1 or the TC stock.

The class 73 was fitted with EP brakes and could control the EP brakes on TC or EMU stock.

 

[darwins]

The difference of a few hundredweight from 1965 to 1969 might just be a matter of which loco you weighed!, but 2 or 3 tons is quite significant. All my sources give the same numbers for the push-pull locos, 77tons 6cwt, hence they were not included in the question.

 

[Taunton]

There are various ways in which weights can be calculated. Fuel tank can be nominally empty, half or full. Diesel fuel weights a bit more than 7lb per gallon, so for 800 gallons that's 2½ tons to play with at the start. Then are weights theoretical, from the initial design drawings (the most common source, like the drawings themselves on which they often appear), or actual, once you have actually built one and weighed it. This can notably differ as well. Then you find that various major spares, such as roof access panels, get replacements manufactured over time by different works in a different way. And of course components that don't work out, and are changed for something different. BRCW may have been given an initial target, say 19 tons per axle, even before design, so it is known initially as a 76-tonner.

If it's any consolation steam locomotives were far more varied, over whether the boiler was filled or not, and very much among themselves individually.

 

[Magdalia]

The diagram books give empty weights and these are consistently 70 tons 9 cwt for the standard loco and 71 tons 4 cwt for the Hastings Gauge loco. So it does look like there are different assumptions regarding fuel when deriving a weight in working order.

 

[GRALISTAIR]

Intuitively I thought the Slim Jims would have been the lightest.

 

[darwins]

The diagram books give empty weights and these are consistently 70 tons 9 cwt for the standard loco and 71 tons 4 cwt for the Hastings Gauge loco. So it does look like there are different assumptions regarding fuel when deriving a weight in working order.

That is interesting. I was recently looking at details of the German V100 locos. In that case they specified that weight in working order was with 2/3 of maximum fuel.

 

[randyrippley]

Intuitively I thought the Slim Jims would have been the lightest.

Don't forget that BRCW were said to have had severe problems in creating the Hastings line body tooling. So severe the delays resulted in damages which destroyed their profitability and hastened their exit from engineering. I wonder if the problem actually related to a weight vs strength tradeoff that they couldn't resolve?
Situation seems even more confusing in that according to some internet tales the Hastings machines were actually ordered first - but built last.

 

[Magdalia]

Situation seems even more confusing in that according to some internet tales the Hastings machines were actually ordered first - but built last.

Those sources are incorrect. The BRCW T3s were ordered in 3 batches of 45 then 20 then 33 to make a total of 98 locos.

The 12 Hastings gauge locos were part of the final batch of 33 locos. They were approved a few weeks before the remaining 21 locos in the third batch, but were built at the end of the third batch not the beginning.