Reciprocating Steam Engine V.S. Compound Steam Engine, Any Difference?

Help Support HMEM:

Joined
Jun 17, 2020
Messages
19
Reaction score
6
Location
usa
Hello,
i don't know what's the difference between the reciprocating and compound steam engine. anyone know?
and I saw this engine. Stirlingkit said it's reciprocating. but I think it's a compound steam engine.😅 am I wrong? help. thanks.

 

Charles Lamont

Well-Known Member
HMEM Supporter
Joined
Mar 24, 2011
Messages
813
Reaction score
263
Location
UK, West Midlands
Reciprocating just means moving backwards and forwards, as opposed to a turbine or Wankel engine. Compound means using the steam twice, partly expanded in a small high-pressure cylinder, and then in a larger, low-pressure one. The engine in question appears to be a twin cylinder, not a compound.
 
Joined
Jun 17, 2020
Messages
19
Reaction score
6
Location
usa
Reciprocating just means moving backwards and forwards, as opposed to a turbine or Wankel engine. Compound means using the steam twice, partly expanded in a small high-pressure cylinder, and then in a larger, low-pressure one. The engine in question appears to be a twin cylinder, not a compound.
so can I call it a reciprocating engine?
 

vederstein

Must do dumb things....
Joined
Feb 26, 2011
Messages
787
Reaction score
577
Any engine with a piston that moves back and forth is reciprocating. The difference with steam engines is that the pistons are often double acting (pressurizes both sides of the piston) where nearly all internal combustion engines are single acting (pressure on one side of the piston exclusively.)

...Ved.

Try this site:

 
Joined
Jun 17, 2020
Messages
19
Reaction score
6
Location
usa
Any engine with a piston that moves back and forth is reciprocating. The difference with steam engines is that the pistons are often double acting (pressurizes both sides of the piston) where nearly all internal combustion engines are single acting (pressure on one side of the piston exclusively.)

...Ved.

Try this site:

great. thank you
 

SmithDoor

Well-Known Member
Staff member
Global Moderator
Joined
Feb 12, 2009
Messages
1,024
Reaction score
144
Location
Clovis Ca
Hello,
i don't know what's the difference between the reciprocating and compound steam engine. anyone know?
and I saw this engine. Stirlingkit said it's reciprocating. but I think it's a compound steam engine.😅 am I wrong? help. thanks.

Since we working with models it come down to witch one do you like.

Dave
 

Steamchick

Well-Known Member
HMEM Supporter
Joined
Apr 2, 2020
Messages
1,252
Reaction score
424
Location
3 Ettrick grove, Sunderland , Tyne & Wear, SR 48
Any engine with a piston that moves back and forth is reciprocating. The difference with steam engines is that the pistons are often double acting (pressurizes both sides of the piston) where nearly all internal combustion engines are single acting (pressure on one side of the piston exclusively.)

...Ved.

Try this site:

MODEL Compound steam twin cylinder engines are much like the performance of a single, but maybe 10% extra, when the steam is super-heated and the engine gets hot to full working temperature. But MODELS are built:
1 for the pleasure of the build,
2 for the pleasure of just running something you have built,
3 for the pleasure of the specific mechanism,
4 for the pleasure of using the power to drive something :- e.g. A boat, a train, a tractor or traction engine, a generator, a water pump, etc.

Moat people recommend you make a single cylinder engine first, then make a twin next. The Stuart kit you ask about (I think) is their single engine with longer crankshaft to make it a twin.
To answer your question about reciprocating vs. compound, the singles, twins and compounds are all reciprocating engines, but the single has 1 cylinder, the twin has 2 cylinders (nearly twice the power, but twice as complicated) and the compound is a twin, as complicated as the twin to make, but uses only the same amount of steam as the single.... so is more efficient.
Enjoy,
K2
 
Joined
Jun 17, 2020
Messages
19
Reaction score
6
Location
usa
MODEL Compound steam twin cylinder engines are much like the performance of a single, but maybe 10% extra, when the steam is super-heated and the engine gets hot to full working temperature. But MODELS are built:
1 for the pleasure of the build,
2 for the pleasure of just running something you have built,
3 for the pleasure of the specific mechanism,
4 for the pleasure of using the power to drive something :- e.g. A boat, a train, a tractor or traction engine, a generator, a water pump, etc.

Moat people recommend you make a single cylinder engine first, then make a twin next. The Stuart kit you ask about (I think) is their single engine with longer crankshaft to make it a twin.
To answer your question about reciprocating vs. compound, the singles, twins and compounds are all reciprocating engines, but the single has 1 cylinder, the twin has 2 cylinders (nearly twice the power, but twice as complicated) and the compound is a twin, as complicated as the twin to make, but uses only the same amount of steam as the single.... so is more efficient.
Enjoy,
K2
and how about this 3 cylinder steam engine? is it better than 2 cylinders?
 

Mechanicboy

Well-Known Member
Joined
Jul 10, 2013
Messages
770
Reaction score
256
Compound steam engine is using less steam than 2 cylinder steam engine and the exhaust of steam is expanding in the next cylinder with large piston diameter for about same effect. To start up the compound steam engine, you need the start valve/simpling valve to send the steam pressure to the low pressure cylinder if the high pressure cylinder has piston in TDC or BDC position who are impossible to start up the steam engine.

The 3 cylinder steam engine in the movie is a waste of steam than 2 cylinder steam engine, but it give more power for same steam pressure. The 3 cylinder steam engines is not compound steam engine.
 

Andy Munns

Active Member
Joined
Feb 6, 2019
Messages
44
Reaction score
13
Location
Australia
Great question - I did not get born knowing this stuff. I remember a long time ago at school my tech drawing teacher taught us the 4 stroke and 2 stroke cycles, and when I became a tech drawing teacher, I remembered and made sure I taught kids this too.

Reciprocating means backwards and forwards, up and down, etc. like a piston, or saw.

All reciprocating steam engines have pistons that go up/down, or left/right, or diagonal...

Simple steam engines use steam in a single cylinder and then exhaust. Simple engines can be double-acting (use steam on both strokes and have a gland) but they can be multi-cylinder simple expansion like most steam locos, winches, etc.

Compound engines use the steam first in a high pressure cylinder (HP) and then get more power from the exhaust in a low-pressure cylinder (LP) - The actual reason they do this is to divide and reduce heat loss from the steam and improve economy. Compounding also helps the engineer start the engine and it reduces the size of components.

You can get triple and quadruple expansion engines as well, usually in ships.
 

L98fiero

Well-Known Member
Joined
Oct 18, 2013
Messages
230
Reaction score
89
Location
Keswick, Ontario
and how about this 3 cylinder steam engine? is it better than 2 cylinders?
As with everything, better is a relative word, if you've never built anything and have no experience machining a simple single cylinder engine might be a good confidence builder but if you have a lot of experience building engines a triple compound might be better. Depending whether you want it to drive something or just have a functional, running engine or a display engine your choices of a better engine will be different, without knowing skill levels or application, better is meaningless.
 

Rocket Man

Well-Known Member
Joined
Nov 4, 2011
Messages
135
Reaction score
34
I want to see a steam engine that does something like a 5 hp steam power lawn mower.
 

Richard Carlstedt

Well-Known Member
Joined
Jul 9, 2007
Messages
124
Reaction score
69
Location
Green Bay ,Wisconsin
Saw a video 25 years ago that showed a British model engineer who took a Stuart Turner ( # 1 ?) engine and mounted it with a small boiler on his reel type lawnmower and he cut grass with it - really neat job.
I have no link, but here are some bigger ones
Rich

 

larryg

Well-Known Member
Joined
Mar 23, 2015
Messages
83
Reaction score
36
Location
Oregon, USA
Saw a video 25 years ago that showed a British model engineer who took a Stuart Turner ( # 1 ?) engine and mounted it with a small boiler on his reel type lawnmower and he cut grass with it - really neat job.
I have no link, but here are some bigger ones
Rich

Maybe this one?


lg
no neat sig line
 
Top