Sep 25 (edited)

Doble F30 Donkey Pump

Following F30 arrival, several decisions had to be made, the real issue with F30, that had never been sorted out, was the fact that it had been built/ordered without an auxiliary unit, this may have been down to cost saving, as the auxiliary unit has more parts than the engine!!!, but reading Marcus Lothrop's notes, he was actually trying to address the issue of the auxiliary unit being driven from the wheels and therefore delivering nothing when stationary, all the main steam car manufacturers from Serpollet 1904 to doble 1930 realised that the pumps needed to work dependant to vehicle movement, Here is the re built doble donkey pump for F30 , although operating independently it was very steam hungry, and did not address all the other features that the auxiliary unit performed.

we have opted to fit an auxiliary to F30 to address these issues and my current thinking is to have the donkey pump come on line when the auxiliary unit is not supplying the required water, this then addresses the issue of water supply at low speeds and negates the in efficiency of the pumps steam usage for the majority of the time as the auxiliary unit will be working

Sep 25, 2026

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Replies (11)

· Sep 25

Isn't this a big issue with the Stanely? Nothing runs unless the car is moving. So you need to hand pump water if the boiler starts to get low.

· Sep 25

it is an issue with a Stanley, although not as critical as with serpollet, white or doble, as they have monotube boilers/generators, no water in is no steam out, the Stanley has a big pot of water so the level may drop but you still have some thing

· Sep 25

@chris I assume this is run on residue steam from the engine heading to the condenser?

· Sep 26

no, this is run on full generator pressure and temperature, no expansion of the steam and exhaust at full pressure and temperature !!!!!!!!!!!! when I first started my Doble journey I visited Norman Shanklin and F34 and was perplexed by zig zag of piping under the running boards, it turns out that this was the exhaust line from the pump and they were trying to loose heat before dumping the exhaust into the condenser, the idea of an independent pump was correct but this was a very in efficient answer to the problem

· Sep 26

Chris, was there not enough excess steam to run it on the engine return?

· Sep 26

that would defeat the object of it running independent to the car moving, however..... a little later in NZ (1931) A & G Price were working on the same issues and designed a vee twin auxiliary unit that did all the functions that the model E auxiliary unit did and was, as you say driven from the exhaust back pressure, and to address the issue of being independent to the vehicle moving there was a steam blead via a diaphragm that added steam if the exhaust pressure dropped

· Sep 26

That make sense to me. I guess the other way to do it is run it off an electric motor. Did anybody try that?

· Sep 27

everybody tried that, F30 had and electric scavenge pump from the condenser back to the water tank, an electric water pump an electric fuel pump, every corner of the water tank had been cut out to allow the room for more and more pumps and shafts, mostly because there was no auxiliary unit, which performed most tasks, see my earlier video post filmed under F30. the main issue with electric is that when the car is making steam or stationary it is not generating any power, unlike an IC car when the engine is idling the battery is still getting a charge the demand on the battery can get too much

· Sep 27

the second video on" F30 Auxiliary's" on this forum shows under F30

· Sep 26

What set ups do Leno's cars have?

· Sep 27

original