On 16 November 2024 at 08:44 Weary Said:

Hello Conrod,

So you have fixed on a final gearing of 2.9 to one, a little greater reduction than the prototype; any idea what kind of ‘cruising-speed’ that will give you?   I’m not sure how-many rpm the engine will run-at otherwise I’d calculate it myself.

Cracking good question.  My guess is the scale speed should be extremely slow.   The Shay started as a light cheap engine designed to run up woody hills on a temporary tramway.   Tramways of this type were often too cheap, narrow gauge, with tight curves and steep slopes.  The track was massively under-engineered compared with a passenger railway, so likely to move vertically and for heavy engines to grind and push the curves over, and derailing.   Ordinary locomotives didn’t work well because they tend to hammer the track, which lightly laid rails can’t manage, and to rock the rails sideways due to the pistons applying torque alternately to the wheels on either side.   The Shay is much kinder to dodgy track:  the gears reduce hammer and apply torque to all the drive wheels at the same time.  The engine also accommodates quite extreme vertical track movement with a comprehensive spring suspension, and the drive wheels are mounted on trucks that follow the curves without stressing them much.   The gearing also allows the engine to climb exceptionally steep inclines, which much reduces the cost of laying the tramway.    In short, a really good engine for logging.

There’s always a downside!  Gearing down means lubrication problems, noise and slow speed.   I guess full size ran at about 4-5mph (brisk walking speed), and would be amazed if one managed 20mph!   So, an authentic model should crawl!

Keeping the exposed complicated Shay gearing lubricated must have needed constant attention on a full size engine.  Not a problem on a model.  The authentic noise is more difficult.   Listening to a YouTube video of a Shay hauling passengers in this century suggests they were quite civilized – a moderate rumble with a some thudding.   But I think this is misleading – the modern video records the sound of a well-maintained lightly loaded Shay run gently on passenger grade track.   I guess a busy Shay with loose gears and worn bearings that was working hard in the woods on a poorly laid logging tramway would be very noisy.

Personally, though I like authenticity, a quiet model Shay running at a speed that pleases the eye without crashing is probably best!

Good to see your progress and nice engineering,

Phil

Congratulations to conrod, thanks for sharing.   Lovely job, please keep up the good work.

Dave

Shays can be noisy.

Shay #3289, oil fired, running with reduced boiler pressure, in order to sand the flues, I’d put engine brakes on full, throttle wide open, while the fireman sanded via the fire door sight hole. It was the only time it made a lot of noise.

Used to spend time at the Roaring Camp in California, volunteer, and their shays/heisler would make a lot of noise going up their steep grades.

Used to volunteer on an ex. CPR light pacific – about the same size as an A4. Used to think it was like riding a dragon; sitting, slight hissing, the odd creak, and humming of the dynamo, then, leaving, it was noise, noise, noise! Fortunately, oil fired, when owned by the CPR it was coal/stoker fired.

The light pacific – we used to do “run pasts” where we’d drop passengers off in a field, back up a mile or so, Check water level, when the engineer deemed the half plus a bit of water was adequate – then full throttle, scream past, hit the brakes and back up. As fireman, when throttle opened, fuel had to be correct (or else the fire was pulled out), water pump on FULL, the gauge glass would be showing full while accelerating; pass the crowds, then the brakes would be on hard; water would disappear from glass, and we’d go and look to see if it was bobbing just by the top of the bottom nut. (fortunately always saw it; water level in a boiler is not static when moving). Oil firing – the fireman and engineer had to be in sync.

Anyway, steam locomotives can be very quiet, until they are asked to do real work!

Oh – and Shays came with different gear ratios; I seem to remember that years ago one in preservation had gears changed with old gears from somewhere else for “faster” operation.

JohnS