Reciprocating mass instead of flywheel?

I know it sounds daft but wondered if it had been done using a vertical weight raised by the power stroke. It'd still need some sort of crank to get round the dead centres? But if one was after a reciprocating power output (as in saw/filer) it might be more compact?

pgk

Steam Hammer ?

Don't see how that would work...If at TDC, what would make the crank continue round - and if there is some strange force that could make it turn, why not turn the other way - its 50:50 as to which way it would go then as its only a weight pushing down linearly. How would you generate the reciprocating motion if starting with rotary motion? ( In your saw/filer..) If not starting with a rotary motion, then a piston arrangement, air/steam/solenoid driven would work fine, but has no need of a crank - other than the operator...

Joe

Steam pumps seem to manage OK.

Would you have to gear it 2:1 as you say you want to raise the weight on the power stroke so most steam engines are double acting but that may help if the dropping weight were used to carry it over TDC and BDC

Flywheels store kinetic energy, wouldn't a pendulum be better?

Try Stewart Harts Dake engine. No flywheel required at all. He has included one but during the build he confirmed it would run without one

Stewart Hart Dake engine

Pete

Please explain the motion - the statement 'Steam pumps seem to manage OK' is pehaps just a little arrogant...

pgkpgk implies/mentions/questions a crank in the process - your statement implies no crank, but a double acting piston cylinder arrangement - in which I presume the piston is forced one way by the pressure of steam/air/ or whatever, on the one piston face, and when topped out, the force is applied to the other face, pushing the piston the other way. There is no crank involved, and so the discussion is moot.

You statement still talks of BDC and TDC, so , mixing concepts again, I assume you are converting linear motion to rotary - which was not part of PgkPgk' question, but nevertheless, the same problem manifests - if there were no flywheel impetus at all, there is no reason for the crank to go round once TDC or BDC is reached.

Perhaps PGK could explain a little more as to what he has in mind?

Joe

2nd one down is what you need

Posts crossed, I don't see the need for a crank on a filing or sawing machine and like above shows TDC would be when piston is at one end of stroke, BDC at other

Edited By JasonB on 16/06/2020 10:40:54

I can see Jason's suggestion of 2:1 gearing working.

You could even use a spring which would be even more compact.

I suspect the answer is partly the extra complexity and partly that the energy stored by a flywheel is related to the square of its speed, while the energy in a raised mass is directly proportional to its height.

This means a flywheel can give proportionally more energy for a small change in speed, and as the purpose of such a devices is to reduce the change in speed over a rotation a less massive flywheel will do the job more efficiently.

Neil

How about a pendulum that swings right round into a complete circle.

We could call it a pendwheel

Neil

Unfortunately those posts are 2012 era, and none of the associated videos of operation seem to be around any more - however, all articles I come across with google seem to show a flywheel as part of the thing - even when masquerading as a 'pulley'...Also could not find anywhere where in Mr Hart's post where he mentions the no flywheel bit?

Final thought,

Various multi-cylinder designs work without flywheels, anything will rotate continuously if it doesn't have dead spots.

The real function of the flywheel is to smooth the motion, this is why water power was still preferred to steam for spinning yarn in the early days and also what led to the invention of the governor.

Mine and feed pumps have no need for smooth, constant delivery of power so don't have flywheels.

What about steam locomotives? They don't have flywheels but use the massive momentum of the whole machine to smooth their motion. There were some notoriously unbalanced locos that used to sway or hammer the tracks due to poor balance.

Much lighter steam cars had flywheels, as did road locomotives that usually had to function as stationary sources of power. Steam wag(g)ons were bigger and heavier and usually had multi-cylinder engines.

The real answer, I suspect, is that adding a reciprocating mass (a) creates challenges in tuning it to match different engine speeds and (b) requires a level of extra complexity that could be used to add a second set of cylinders.

Neil

Or an angularly-disadvantaged flywheel..

Really final thought...

Early steam pumps, did use a reciprocating mass, in the form of a heavy beam.

Neil

Still do not agree!

They certainly have flywheels! The Linear motion is converted to rotary by the very wheel on which the loco runs, and so as the loco moves, its massive momentum forces the wheel to turn, forcing the crank to move...The loco, its, weight and momentum, and the coupled rotary to linear motion is precisely what a flywheel is, no?

Joe

So if you did want a crank and TDC/BDC this is how I saw the geared weights working.

The double acting piston would connect to a crank and then to a crankshaft. large gear on the crankshaft would drive smaller gear at 2:1 and weight suspended from smaller gear. on the two power strokes from 45deg to 135deg and 225 to 315 the weight would be lifted. Before the piston gets to TDC or BDC the weight will start to drop and by driving back through the gears will pull the crank over BDC & TDC.

Saw or file could be driven by a second crank off the shaft or linked to the piston one.

That's how I see it working but the saw/filer may jump about a bit as the weight goe sup and down

Edited By JasonB on 16/06/2020 10:55:49

? Not because water was free and steam cost coal then. I understood that early installations used steam engines to pump water back up hill in times of drought. Easy to install too as all the drive machinery from water wheel upwards was allready in place.

Just a comment.

regards Martin

As I said, that is a double acting cylinder with NO CRANK. Obviously such a mechanism works fine - the motion is generated linearly from the start - there is in fact no TDC or BDC - the motion changes direction when the appropriate valve is actuated.

If PGK drops the thought of a crank in his mechanism and uses a double acting cylinder, then , well, nothing to discuss..

Edited By Doubletop on 16/06/2020 11:20:42

Surely you dont want a reciprocating weight because it takes energy to slow it down, stop it and then reverse its direction at the end of each stroke? Sounds horribly low efficiency doesnt it, like Neil's beam engine?

Edited By Hopper on 16/06/2020 11:22:53