A railway water lift of this type uses a water trough laid between the rails. A scoop below a moving locomotive tender lowers into the trough, and the train’s forward motion directs water up a duct into the tender tank. This track-pan system serves a moving train rather than filling a stationary water crane.
Railway Water Lift Interactive Calculator
See a tender scoop lower into a between-rail water trough. Explore passage time, ideal intercepted flow, and pickup using a user-entered capture factor.
Equation Used
- The effective opening stays immersed for the entered trough length.
- Capture factor is supplied by the user because it depends on scoop geometry, immersion, pipe losses, splash and overflow.
- Constant train speed, steady trough level and no tender overflow.
- No scoop drag, structural load, pipe loss or safe-speed prediction.
The diagram shows the between-rail trough and tender scoop documented in Hiscox movement 1649o and historical water-scoop patents.
A lowered scoop takes water while the train is moving
Hiscox movement 1649o shows a long trough between the rails and a movable tender spout lowered at an angle. The 1908 Bennett patent likewise describes a hinged scoop entering a track trough and directing water through a duct into the tender.
The animation keeps those parts explicit: rails, between-rail water trough, moving tender, water tank, delivery duct and hinged scoop. The water path is schematic and no historical dimensions are implied.
Long-distance steam operation without a water stop
Track pans or water troughs let suitably equipped steam locomotives replenish the tender while moving. They were route infrastructure, not a general-purpose pump. Crews had to lower and raise the scoop within the trough limits and avoid overfilling the tender.
Ideal swept-volume exploration
The calculator uses passage time t=L/v, ideal intercepted flow Q=Av, estimated pickup V=Q·t·η, and velocity head h=v²/(2g). The capture factor η is an explicit user input because real pickup depends on scoop geometry, immersion, pipe losses, splash and overflow.
This is not a scoop-load, drag, structural or safe-speed design calculation.
Worked idealized example
At 45 mph over a 1,200 ft trough, passage takes about 18.2 seconds. With a 50 in² effective opening, ideal intercepted flow is about 171 US gal/s. A user-entered 65% capture factor produces an estimated 2,024 US gal, about 40.5% of a 5,000 gal tender. These values are an ideal exploration, not a historical performance guarantee.
What changes the result
A longer trough or larger effective opening increases ideal pickup. Higher speed shortens passage time but increases intercepted flow and velocity head; in this simplified swept-volume model those two speed effects cancel in total volume. Real equipment does not follow that cancellation exactly because losses, splash, immersion and operating constraints change with speed.
Railway water-trough questions
Where is the trough?
It lies between the running rails so the tender scoop can enter it while the train passes.
Why is capture factor an input?
The cited historical drawings establish the mechanism but do not provide one universal efficiency for every scoop, duct, speed and trough.
Does velocity head size the scoop?
No. It is only v²/(2g), a useful ideal comparison. This calculator does not predict drag, impact load or structural safety.
Why can total ideal pickup be independent of speed?
In V=Av(L/v)η, speed raises flow by the same factor that it shortens passage time. Real systems add speed-dependent losses and limits.
Primary references
- Gardner D. Hiscox, Mechanical Movements, Powers, Devices and Appliances, p. 396, movement 1649o — trough between tracks and movable tender spout.
- Arthur Bennett, US901315A, Water-scoop for locomotive-tenders (1908) — hinged scoop, track trough, duct and tender water path.
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