Tender wheelset

Hello!

Looking at the "Greyhound" or LSWR T9 steam locomotive it has this 4 wheeled tender whitout any frames outside the wheels , so, to mee it looks a bit odd or "naked". This sort of tender were also used behind the "Great Bear" I assume. "Gladstone had a 3 wheeled tender also without outside frames.
Was it any particuliar reason for such an unusual construction? To save weight?

Knut

 

The tender coupled to the T9 120 is known as a "water cart tender". Though I don't think that was the official title. Other former London & South Western Railway [designed] loco's like the S15 825 on the N.Y.M.R. also had similar bogie tenders. It boiled down to the L.S.W.R. not having water troughs on their long mainline to the West Country, so in order to give the loco a reasonable amount of water for the run they fitted it with a large 8 wheeler tender with plenty of water capacity for the journey from Waterloo [London] towards Exeter.

Edit: Forgot to say that the 8 wheeler bogie tenders coupled to the likes of 825, had more conventional bogies with outside frames.

 

The story behind the Great Bear tender is said to be that Churchward looked at the initial drawings for the Bear and thought the tender looked too small, so he asked for a longer one. The bogies were based on standard locomotive bogies, but shortened. Supposedly the reasons for its creation were purely aesthetic. Its certainly recorded as holding the same amount of coal and water as contemporary 6 wheeled units.

 

I believe Stroudley's idea was to use the same wheelset design for the training axle and the tender axles on the "Gladstones", an erly form of standardisation. Dugald Drummond, the designer of the T9, worked under Stroudley at Lochgorm and Brighton. The wheel diameter on the watercart tenders was the same as on the loco bogies on many Drummond and Urie LSWR engines so Drummond probably followed Stroudley's idea. I believe the Highland Railway casle class engines also had inside bearings on their bogie tenders; these were designed by Peter Drummond, younger brother of Dugald

 

Many thanks for reply everyone of you!