Things you always wanted to know the answer to [Vol. 4]
Discussion
Why don’t steam locomotives have gear boxes?
In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
Ayahuasca said:
Why don’t steam locomotives have gear boxes?
In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
I'd imagine a gearbox would be very difficult and expensive to engineer strong enough, introduce extra friction, hard to manually shift, and be prone to wear and breaking.In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
Ayahuasca said:
Why don’t steam locomotives have gear boxes?
In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
You can't stall a steam engine. Any excess pressure is allowed to escape through a release valve.In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
I think I'm right in saying that the gear box is effectively the amount of heat / pressure that's allowed to build.
SpeckledJim said:
Ayahuasca said:
Why don’t steam locomotives have gear boxes?
In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
I'd imagine a gearbox would be very difficult and expensive to engineer strong enough, introduce extra friction, hard to manually shift, and be prone to wear and breaking.In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
They said the Diesel-Electric was developed because a suitable gearbox to directly drive the wheels would have been bigger than the locomotive itself, would have weighed an inordinate amount, and would have seized from its own friction. Basically it would have been technically unfeasible.
I presume the same would be true for a steam engine.
Clockwork Cupcake said:
SpeckledJim said:
Ayahuasca said:
Why don’t steam locomotives have gear boxes?
In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
I'd imagine a gearbox would be very difficult and expensive to engineer strong enough, introduce extra friction, hard to manually shift, and be prone to wear and breaking.In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
They said the Diesel-Electric was developed because a suitable gearbox to directly drive the wheels would have been bigger than the locomotive itself, would have weighed an inordinate amount, and would have seized from its own friction. Basically it would have been technically unfeasible.
I presume the same would be true for a steam engine.
) that steam engines' torque characteristics are more akin to an electric motor than internal combustion. i.e. much torque at zero revs.They do however vary the length of piston stroke over which steam is admitted to the cylinder. Zero revs - most of the stroke, high revs - less. Called cutoff IIRC.
wiki
jet_noise said:
I've got in mind (until someone with real knowledge arrives ) that steam engines' torque characteristics are more akin to an electric motor than internal combustion. i.e. much torque at zero revs.
They do however vary the length of piston stroke over which steam is admitted to the cylinder. Zero revs - most of the stroke, high revs - less. Called cutoff IIRC.
wiki
Fascinating! Thank you for that. ) that steam engines' torque characteristics are more akin to an electric motor than internal combustion. i.e. much torque at zero revs.They do however vary the length of piston stroke over which steam is admitted to the cylinder. Zero revs - most of the stroke, high revs - less. Called cutoff IIRC.
wiki
Ayahuasca said:
Why don’t steam locomotives have gear boxes?
In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
If they can break traction with direct drive then a gearbox would only multiply the problem. In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
It would be hugely complicated to add a gearbox. The wheels are directly connected to the pistons (mechanically its like the crank in a car).
It can't stall because it's not "running" like a car. Energy is stored in steam pressure, which can be applied slowly onto the piston, causing it to start moving, which starts moving the wheels.
Cars can stall because internal combustion engines need to run at a minimum speed, but cars need to be able to stop or move slower than the gearbox will allow.
Edited by 98elise on Sunday 19th July 15:36
I have been warned, and now started warning others, that it is bad form to support cars on bricks because bricks have a habit of exploding, or cracking and collapsing. Not suitable to hold up a car while you work under it.
But, why don't the bricks at the bottom of a 5m tall wall explode? They must have more than the weight of one corner of a car on them, surely? Or is the whole thing rubbish?
But, why don't the bricks at the bottom of a 5m tall wall explode? They must have more than the weight of one corner of a car on them, surely? Or is the whole thing rubbish?
2 sMoKiN bArReLs said:
Frank7 said:
SpeckledJim said:
We have Postmen
Who work for the Royal Mail
The Americans have Mailmen
Who work for US Post
What's going on with that then?
Staying with that theme,Who work for the Royal Mail
The Americans have Mailmen
Who work for US Post
What's going on with that then?
We pay bills with cheques,
They pay checks with bills.
RATATTAK said:
2 sMoKiN bArReLs said:
Frank7 said:
SpeckledJim said:
We have Postmen
Who work for the Royal Mail
The Americans have Mailmen
Who work for US Post
What's going on with that then?
Staying with that theme,Who work for the Royal Mail
The Americans have Mailmen
Who work for US Post
What's going on with that then?
We pay bills with cheques,
They pay checks with bills.
2 sMoKiN bArReLs said:
RATATTAK said:
2 sMoKiN bArReLs said:
Frank7 said:
SpeckledJim said:
We have Postmen
Who work for the Royal Mail
The Americans have Mailmen
Who work for US Post
What's going on with that then?
Staying with that theme,Who work for the Royal Mail
The Americans have Mailmen
Who work for US Post
What's going on with that then?
We pay bills with cheques,
They pay checks with bills.
A bum is a tramp
And s tramp is s slag
Ayahuasca said:
Why don’t steam locomotives have gear boxes?
In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
Basically because there's no need! In films you see them spin their wheels as they gain traction, but you never see them start in a low gear, then change up, etc.
Why no multi-speed gearbox ?
And in the absence of a gearbox, why doesn’t the engine ‘stall’ on starting off? Can steam engines stall?
As the movement is provided by steam pressure acting on the piston, it can't really "stall", although I suppose if the load was more than the steam pressure could overcome then it might just not go anywhere, but wheel slip is much more likely.
The cranks on the wheels are set so that at least one of the pistons will be on its power stroke, so it doesn't need an initial "spin" to get going.
Along with the regulator which acts like a throttle, the cut-off determines when in the cycle the inlet valve to the cyclider is open - although not a gearbox this is adjusted depending on speed and load to give enough (but too much!) torque when starting, and improving efficiency at higher speeds.
Some steam locomotives have a fixed reduction gear system though, as do traction engines.
droopsnoot said:
I have been warned, and now started warning others, that it is bad form to support cars on bricks because bricks have a habit of exploding, or cracking and collapsing. Not suitable to hold up a car while you work under it.
But, why don't the bricks at the bottom of a 5m tall wall explode? They must have more than the weight of one corner of a car on them, surely? Or is the whole thing rubbish?
Because mortar spreads loads equally, which is something bricks are good at handling.But, why don't the bricks at the bottom of a 5m tall wall explode? They must have more than the weight of one corner of a car on them, surely? Or is the whole thing rubbish?
Whereas the point load of a poorly supported car onto a single brick, which is also poorly supported by other bricks, might well crack.
A little tap from a hammer will crack a brick in half, but the same tap on the top of a wall does nothing.
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