Giles
Western Thunderer
Two of the cranks, courtesy of the Stepcraft (17 minutes each!)
Aspartic Cranks by giles favell, on Flickr
Aspartic Cranks by giles favell, on Flickr
Giles' misc. Work bench.
- Thread starter Giles
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Giles
Western Thunderer
“thank Heavens for collets!”
I suspect GJC said something similar
Ah.... the green things with the regulator's on the wrong side.....
Sadly, I've always found it takes rather too long to make those things..... I've never perfected it....
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Giles
Western Thunderer
The first two bogies assembled. Only one motor in place, and the motors gear not yet fitted. The gear motor is one of the erstwhile useless 8mm 40rpm gearmotors with one planetary stage removed to give a very useful 150rpm.
The bolster is printed in PLA for strength, and includes a hole through to accommodate the gearmotor at the correct diameter, position and angle for meshing. On top is a sphere for pivot and snap fixing.
Yorkshire Dave
Western Thunderer
Hi Giles,
Having seen your drive mechanisms for road vehicles could you have used a similar drive for this diesel?
Mount the motor in the body and drive through a gearbox to the propshafts.
Having seen your drive mechanisms for road vehicles could you have used a similar drive for this diesel?
Mount the motor in the body and drive through a gearbox to the propshafts.
Giles
Western Thunderer
Hi Dave,
Yes, I could have done - it was a toss-up! That of course is precisely how the real thing was done, but they found the had to fit a diff in the centre between the bogies, as they were getting 'wound up'!
The idea of short shafts and sliding couplings together with a fixed gearbox on each bogie made me plump for dual motors!
Yes, I could have done - it was a toss-up! That of course is precisely how the real thing was done, but they found the had to fit a diff in the centre between the bogies, as they were getting 'wound up'!
The idea of short shafts and sliding couplings together with a fixed gearbox on each bogie made me plump for dual motors!
Osgood
Western Thunderer
That is quite - well, actually very - surprising. I guess they tried without one first and had some transmission breakages.
Was it that a bit of wheel slip on one bogie would mess everything up?
Osgood
Western Thunderer
I'm really not sure, Graham - wheel slip at one end would just mean the torque to that end would be lost, but the torque to the other bogie would remain smooth and constant.
It is essentially the same mechanical layout as a double drive truck bogie (albeit simplified by the omission of axle differentials - not required).
In the 40s and 50s not many heavy double drive trucks had an inter-axle diff - albeit any variation in 'wheel travel 'between axles could be absorbed by the flexible tyre.
But virtually all variation occurs across the axle, very little between axles.
One might imagine with the locomotive that any variations that might occur (and which would surely be very minor compared to the truck application) would be relieved by the initiation of wheel slip on one bogie.
The evidence however shows that significant wind-up occurred, necessitating the use of a diff.
Im sure if I had designed the transmission I would have fallen into the same trap - neatly avoided by Giles.......
It is essentially the same mechanical layout as a double drive truck bogie (albeit simplified by the omission of axle differentials - not required).
In the 40s and 50s not many heavy double drive trucks had an inter-axle diff - albeit any variation in 'wheel travel 'between axles could be absorbed by the flexible tyre.
But virtually all variation occurs across the axle, very little between axles.
One might imagine with the locomotive that any variations that might occur (and which would surely be very minor compared to the truck application) would be relieved by the initiation of wheel slip on one bogie.
The evidence however shows that significant wind-up occurred, necessitating the use of a diff.
Im sure if I had designed the transmission I would have fallen into the same trap - neatly avoided by Giles.......
simond
Western Thunderer
I'm really not sure, Graham - wheel slip at one end would just mean the torque to that end would be lost, but the torque to the other bogie would remain smooth and constant.
It is essentially the same mechanical layout as a double drive truck bogie (albeit simplified by the omission of axle differentials - not required).
In the 40s and 50s not many heavy double drive trucks had an inter-axle diff - albeit any variation in 'wheel travel 'between axles could be absorbed by the flexible tyre.
But virtually all variation occurs across the axle, very little between axles.
One might imagine with the locomotive that any variations that might occur (and which would surely be very minor compared to the truck application) would be relieved by the initiation of wheel slip on one bogie.
The evidence however shows that significant wind-up occurred, necessitating the use of a diff.
Im sure if I had designed the transmission I would have fallen into the same trap - neatly avoided by Giles.......
Tony,
it’s not necessarily the case, it might be that the uj’s, splines, or the shafts themselves, simply were not up to the torque that was necessary to break traction at one or the other bogie (which would cancel any inter-bogie wind-up), in which case the spines would wear, or jam, or the uj’s would shred themselves. All of which might be cheaper to correct with a diff, than by beefing it all up to the required capacity.
that said, the diff can’t have been cheap…
atb
Simon
Dog Star
Western Thunderer
I think that I have related this snippet before; in the early 1970s Old Oak had need of tyre turning for a Hymek... for expediency the engine was sent to Stratford for the work. Nobody at Stratford had encountered one of these beasts before and nobody on the WR thought to advise of the correct procedure. Stratford turned the wheels and returned the engine. The damage was done by the time that Old Oak received the loco. A Hymek requires that all wheels are of the same diameter to a fine degree and that was not done in this instance. Whether the damage was to a gearbox or to one/more cardan shafts is lost in the mists.
Suffice to say, the fitters at Didcot enjoyed discussing the finer points with the GWS volunteers as at that time there were several Hymeks which "shared" shed space with 6998, 6106, 1466 and several industrials.
regards, Graham
Suffice to say, the fitters at Didcot enjoyed discussing the finer points with the GWS volunteers as at that time there were several Hymeks which "shared" shed space with 6998, 6106, 1466 and several industrials.
regards, Graham
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Yorkshire Dave
Western Thunderer
Could haberdashers press studs/snap fasteners have been used for the truck/bogie mounting or do they require more force than the wire system you've designed?