Reciprocating mass instead of flywheel?

[JasonBModerator @jasonb]

I would have said the mass (weight) is reciprocating. OP did not stipulate whether his crank should only act in an arc or full circle

[pgk pgkParticipant @pgkpgk17461]

Thanks for all the comments, folks.
This was just something that popped into my head since we seem to be converting reciprocating power to rotary and ( re the die filer thread) then taking rotary power to convert to reciprocating.

In my mental image of an idea I was stuck thinking single acting which needs a boost around the dead ends thus the addition of a crank at the bottom of the weight travel to swing it over. Double acting as per the steam hammer negates that and could be the basis of a simple air driven filer?

I reckon jason could have one knocked together by the weekend….

pgk

[duncan webster 1Participant @duncanwebster1]

Posted by JasonB on 16/06/2020 13:23:11:

I would have said the mass (weight) is reciprocating. OP did not stipulate whether his crank should only act in an arc or full circle

The weight is reciprocating, as is the spring (sort of) but the thing which is lifting the weight is rotating, just not around its centre of mass. You can use reciprocating masses as a sort of flywheel, I once had to work out the energy stored in the pistons/rods etc of a multi cylinder diesel engine, not quite sure why, but it was interesting at the time. The phase difference between the weight going up and down and the power strokes of the engine will be important. First guess is that the weight should be at the bottom of it's stroke (max acceleration) when the engine is at the middle of it's powered stroke

Edited By duncan webster on 16/06/2020 14:25:53

[not done it yetParticipant @notdoneityet]

I admit to not reading all the thread so may be repeating what has preceded.

The whole idea of this drake engine is that there is no net stored energy? Equal masses travelling in opposite directions will balance out the forces in any one direction, when stopping ie momentum of the system will be zero, or f=ma = zero.

Rotating flywheels actually store energy which is available to be recovered while slowing down.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Bazyle on 16/06/2020 12:00:56:

…

The governor was invented for regulating windmills long before Watt sneekily patented it and severely restricted the progression of the art of grinding flour as he did with the crank which held back steam engine development by a decade.

I don't think Watt patented either! His wheel and planet gear was invented to circumvent the crank patent held by James Pickard. The centrifugal governor was invented by Huygens who died 40 years before Watt was born. Hard to see how the art of grinding flour was held up!

Free the James Watt One! Or maybe not. Bazyle's examples may not be right but Boulton and Watt certainly were guilty of slowing steam engine development by grabbing patents and rubbishing new ideas. It became a feature of British industry – once an idea is accepted, old boys fight tooth and nail to resist further innovation. Metrication? Not in my back yard!

Dave

[BazyleParticipant @bazyle]

Just re-read my 500 page copy of Watt's biography and I do appear to have miss-remembered that part of the book.

[Howard LewisParticipant @howardlewis46836]

Assorted musings

The mention of steam pumps brought to mind the reciprocating pumps of the Worthington Simpson kind.

These used what I would call a form of gab gear to operate the steam valve to reverse the motion of the power piston.

(In a similar way to quickly flinging the reversing lever from forward to reverse, and back again, on a steam locomotive. )

Beam engines of the Cornish type used the steam power to raise the pump rods. The majority of the pumping was done by the weight of the massive wooden pit gear driving the pump plunger down. Until Trevithick, steam pressures were of the order of only 5 psi. He advocated using "Strong Steam" at 40 psi.

The valves ("nozzles" ) were controlled by tappets, which could be moved, on rods connected to the beam, and so directed steam to upper or lower side of the piston to cause the beam to reciprocate.

The beam engines at Coleham Head, in Shrewsbury pumped 112 and 114 gallons at each stroke. These engines were rotative, and had flywheels some 11 feet in diameter.. Normally, they ran at 11 rpm. At 16 rpm they were reputed to shake the building!

The flywheel basically stores kinetic energy to provide momentum to carry the crankshaft through the points where the piston is producing little or no rotative power, and by absorbing energy during the power strokes serves to damp out the power surges and deliver a more even delivery of torque. In effect it decreases angular acceleration during the power stroke, but increases it during idle strokes.

It does not do this totally effectively. Witness the torsional oscillations at the free end of a crankshaft, when an engine is under load, although torsional flexibility of the crankshaft effects the magnitude of the vibration.

The hammer blow referred to in connection with steam locomotives, most obvious in two cylinder locomotives, is the result of the secondary forces resulting from balancing the primary forces. (piston, connecting rod, and crankpin ) Multi cylinder locomotives, particularly four cylinder, with divided drive, used the forces generated by one pair of cylinders to counteract those produced by the other pair.

Attempts to minimise hammer blow on two cylinder locomotives had the side effect of producing a fore and aft oscillation, which was most prevalent in the first coach of the train.surge.

Possibly, connecting the piston rod to a pendulum would cause enough energy to be stored to run the egine through the inner and outer dead centre positions.

Howard

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