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logoman

Cheddar Gemini and MH&B PB2

A side by side comparison of the Cheddar Gemini (the green engine) and the Marten Howes & Baylis PB2.
When MH&B stopped producing engines they lent the plans to Cheddar so that they could supply them with a similar engine for their boat kits.
Cheddar made some changes to the MH&B design and produced another great engine.





steamyjim

Both very very nice! But if I had to chose one, got to be the Gemini
logoman

steamyjim wrote:
Both very very nice! But if I had to chose one, got to be the Gemini


why is that Jim?
mogogear

So Mils,, the steamchest mounted valve is a "throttle only"  , and the tail shaft gearing is for reversing?

If so a couple of pictures showing the gearing in F and R position please Miles

Thanks and nice looking engines. I have been following Nick Monahan's ( and others) discussions of MH&B and Monhan's Engines over on MBM. They( MH&B) really hand made their engines...all pre-CNC.
Les

Two lovely looking engines but I would go for the Gemini plus a waterpump.
logoman

Greg, there is very little to see between forward and reverse on both engines, just a matter of 100 degrees movement on the lever for the PB2, and only 20 degrees on the Gemini.
STEAMPROPULSION

I did not know the story about the Cheddar/MH&B deal, but I confess, I thought that the two engine were very much alike just by "coincidence", to say the least.
In past years there had been actually a lot of swapping, Jphn Woodroofe of Cheddar being the main actor.
From the boilermaking activity  (for Stuart and Maxwell Hemmens) Cheddar started making the Stuart ST oscillator, widening the oscillators range, in line, V twins etc.
Than the Gemini from MH&B. and Pegasus.
I have a SVS in line twin  which looks very much alike one of Cheddars engines (Plover).
Another mere coincidence or again a deal between steam engine makers?
Now Stuart produces Cheddar designed models.
That's the end of the circle.
steamyjim

logoman wrote:
steamyjim wrote:
Both very very nice! But if I had to chose one, got to be the Gemini


why is that Jim?


I just like how the Cheddar cylinder block is made out of one solid lump and things like the plate supporting the cylinders is made from a single large plate as oppoosed to two cut out sections. The Cheddar engine just looks a bit beefier

The Cheddar Engines also have always been my sort of dream engines since I first visited the factory the first time many years ago
magpie38

logoman, what can I say, stunning, absolutely stunning
duncandumpertruck

In a loutish builders voice he says; "Wot a cracking pair!"  

Lovely engines there Miles. For me if it came down to it the MH&B would be my pick. Are these recent additions?
SlideValve

steamyjim wrote:
logoman wrote:
steamyjim wrote:
Both very very nice! But if I had to chose one, got to be the Gemini


why is that Jim?


I just like how the Cheddar cylinder block is made out of one solid lump and things like the plate supporting the cylinders is made from a single large plate as oppoosed to two cut out sections. The Cheddar engine just looks a bit beefier

The Cheddar Engines also have always been my sort of dream engines since I first visited the factory the first time many years ago


I was about to say the same thing   But i would gladly take either one  
steamyjim

Les wrote:
Two lovely looking engines but I would go for the Gemini plus a waterpump.


Why not the go the whole hog and go for a Proteus with water pump  
Les

steamyjim wrote:
Les wrote:
Two lovely looking engines but I would go for the Gemini plus a waterpump.


Why not the go the whole hog and go for a Proteus with water pump  


I did.
steamyjim

Les wrote:
steamyjim wrote:
Les wrote:
Two lovely looking engines but I would go for the Gemini plus a waterpump.


Why not the go the whole hog and go for a Proteus with water pump  


I did.


Jelous
logoman

steamyjim wrote:
logoman wrote:
steamyjim wrote:
Both very very nice! But if I had to chose one, got to be the Gemini


why is that Jim?


I just like how the Cheddar cylinder block is made out of one solid lump and things like the plate supporting the cylinders is made from a single large plate as oppoosed to two cut out sections. The Cheddar engine just looks a bit beefier

The Cheddar Engines also have always been my sort of dream engines since I first visited the factory the first time many years ago


The reversing mechanism on the Gemini is an improvement, the center of gravity is lower, and i love the green paint. I prefer the individual cylinders of the MH&B though.
logoman

duncandumpertruck wrote:
In a loutish builders voice he says; "Wot a cracking pair!"  

Lovely engines there Miles. For me if it came down to it the MH&B would be my pick. Are these recent additions?


I've had the MH&B for a while, but the Gemini is new, and my first Cheddar engine.
steamyjim

logoman wrote:
steamyjim wrote:
logoman wrote:
steamyjim wrote:
Both very very nice! But if I had to chose one, got to be the Gemini


why is that Jim?


I just like how the Cheddar cylinder block is made out of one solid lump and things like the plate supporting the cylinders is made from a single large plate as oppoosed to two cut out sections. The Cheddar engine just looks a bit beefier

The Cheddar Engines also have always been my sort of dream engines since I first visited the factory the first time many years ago


The reversing mechanism on the Gemini is an improvement, and i love the green paint. I prefer the individual cylinders of the MH&B though.


I think maybe the induvidual cylinders combined with the cylinder mounting plate on the Gemini would look good! Less flimsy looking IMHO. I appreciate it is not flimsly by any means, just has less of a substantial look to it.

What is the improvement on the reversing gear? Needs less movement which allows easier conversion to RC?
logoman

steamyjim wrote:


What is the improvement on the reversing gear? Needs less movement which allows easier conversion to RC?


The MH&B engine uses a quadrant gear acting on a viton ring with a slip eccentric, and whilst I like the uniqueness of this arrangement, I worry that the viton will deteriorate one day. As you say, less movement needed for the Gemini is also good.
kusuchi

They both look great, but the PB2 has it for me!

Guess I'm just an M,H, & B aficionado.  Peter Baylis did design some wonderful engines.  I'm just astounded by the way the PB3 propels the 20 lb Der Seekadett through the water.  

We just need to get the PB4 from Nick, and the M.H & B double boiler back from Russia!
logoman

kusuchi wrote:

We just need to get the PB4 from Nick, and the M.H & B double boiler back from Russia!


there's a plan.
logoman

logoman wrote:
steamyjim wrote:


What is the improvement on the reversing gear? Needs less movement which allows easier conversion to RC?


The MH&B engine uses a quadrant gear acting on a viton ring with a slip eccentric, and whilst I like the uniqueness of this arrangement, I worry that the viton will deteriorate one day. As you say, less movement needed for the Gemini is also good.



Ah, I forgot to mention that the MH&B engine should be stopped before reversing, but the Cheddar need not (as far as I'm aware).
Ross

Beautiful pictures of beautiful engines!
steamyjim

logoman wrote:
logoman wrote:
steamyjim wrote:


What is the improvement on the reversing gear? Needs less movement which allows easier conversion to RC?


The MH&B engine uses a quadrant gear acting on a viton ring with a slip eccentric, and whilst I like the uniqueness of this arrangement, I worry that the viton will deteriorate one day. As you say, less movement needed for the Gemini is also good.



Ah, I forgot to mention that the MH&B engine should be stopped before reversing, but the Cheddar need not (as far as I'm aware).


Is that to reduce wear on the viton ring? Or for some other reason?
logoman

steamyjim wrote:
logoman wrote:
logoman wrote:
steamyjim wrote:


What is the improvement on the reversing gear? Needs less movement which allows easier conversion to RC?


The MH&B engine uses a quadrant gear acting on a viton ring with a slip eccentric, and whilst I like the uniqueness of this arrangement, I worry that the viton will deteriorate one day. As you say, less movement needed for the Gemini is also good.



Ah, I forgot to mention that the MH&B engine should be stopped before reversing, but the Cheddar need not (as far as I'm aware).



Is that to reduce wear on the viton ring? Or for some other reason?



it could be, but the instructions inform that it is to remove the boiler pressure on the slide valves and allows the reversing lever to turn the eccentrics more easily.

In practice it is difficult to say if this is really necessary, it will easily reverse while under pressure, but I will stick with it.

repost:
logoman

logoman wrote:
steamyjim wrote:
logoman wrote:
steamyjim wrote:
Both very very nice! But if I had to chose one, got to be the Gemini


why is that Jim?


I just like how the Cheddar cylinder block is made out of one solid lump and things like the plate supporting the cylinders is made from a single large plate as oppoosed to two cut out sections. The Cheddar engine just looks a bit beefier

The Cheddar Engines also have always been my sort of dream engines since I first visited the factory the first time many years ago


The reversing mechanism on the Gemini is an improvement, the center of gravity is lower, and i love the green paint. I prefer the individual cylinders of the MH&B though.


And the chunkier cylinder block of the Gemini makes it far more susceptible to Hydraulic lock.
kno3

Logoman, are there any differences in running between the 2 engines?
Les

logoman wrote:
logoman wrote:
steamyjim wrote:
logoman wrote:
steamyjim wrote:
Both very very nice! But if I had to chose one, got to be the Gemini


why is that Jim?


I just like how the Cheddar cylinder block is made out of one solid lump and things like the plate supporting the cylinders is made from a single large plate as opposed to two cut out sections. The Cheddar engine just looks a bit beefier

The Cheddar Engines also have always been my sort of dream engines since I first visited the factory the first time many years ago


The reversing mechanism on the Gemini is an improvement, the center of gravity is lower, and i love the green paint. I prefer the individual cylinders of the MH&B though.


And the chunkier cylinder block of the Gemini makes it far more susceptible to Hydraulic lock.


I have the same problem with the Proteus.
STEAMPROPULSION

Les,
have you ever fancied of installing cylinder drain cocks?
Condensate is inevitable in cold cylinders, from the smallest oscillators on.
logoman

I'd like to see a Proteus with drain cocks.
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