Topic: Principle of The Maudslay. (Read 3879 times)

KBIO · « **on:** September 13, 2020, 06:55:34 pm »

Hello!
To follow my last post on the PB2 reverse explanation, I propose the following one on how works a Maudslay reverse. I am sure that a lot of forumers know everything about it but it helps me to understand.
As usual, the video is clumsy but I am sure that you people are able to understand and do not hesitate to tell me if I made mistakes or if there is more details to add.
Thank you for your kind understanding.

>Principle of the Maudslay.
Firts of all it is necessary to understand that the principle is based on 4 dented wheels and to keep the formulas simple we will assume :-1) That they are at the four corners of a parallelogram.
-2) The two on the bottom shafts are the same and the two intermediates are also the same .This keeps the formulas very simple and, believe me,
you most likely don’t want to solve the general case…

Hence, the rotation of the crank shaft is transmitted to the eccentric shaft via the two intermediaries and the rotation of the two shafts is in the same direction and at the same speed.
The gear on the bottom right is tighten on the engine crankshaft . The one on the bottom left is tighten on the eccentrics (sliding valves) shaft.
They do not touch each other.

Explanation:
-The engine is stopped .
Looking at the video, we can see that the control lever pivotes on the crankshaft from the right to the left with an angle of 45°. It is important to keep the 4 gears at the same size to allow this angle of 45°. if not the course of the control lever will be different.
The crankshaft gear does not rotate. Obvious.

Looking at the top right gear, moved by the lever , we can see that it rotates by 90° . Transmitting this rotation to the left gear.
Now looking at the bottom left gear which is free to rotate ,we observe that it makes a complete half turn and rotates by 180°.
This is normal: 90° on the top + 90° on the bottom = 180°
So 45 ° on the lever makes 90° rotation on the two top gears which give 180° on the eccentric shaft.
See the white marks on the gears.
Fantastic ! This is exactly what we need to do for changing the steam inlet in the slide valves box from to top to bottom (for instance).
The engine then , sarts to runs in the other direction.

Now , be careful! We can understand that if I displace the control lever by 47° (instead of 45°) , the two top gears will rotates by 47° X 2 = 94° .
Therefore, the slide valves gear will rotate by 94° x 2 = 188°.
Too bad ! I am out and my timing is wrong. The slide valve is out and the steam does not enter. The engine stops !!
Don’t panic ! To avoid this we can set a bolt at the right side of the control lever and another on the left side of it.
Then , we can adjust exactly the course of this lever to 45° by screwing in or out the two opposite bolts.

The proper adjustment of the slide valves in slide valve boxes are identical of those for classic slide vales engines (ie: Stuart, ….)
The only attention required is to set the timing in a way that the rotation of the engine pushes the control lever in the same direction. This to avoid a force against it.
The great advantge of the Maudslay compared to the Stephenson for example, is that we can set the exact timing while the engine is running!
Magic !
Mr Maudslay (1771-1831) Respect! You are a genius!! And this is a Breton who tells it! But coming from a country who invented the « Happy Hours » , second major invention, this is not surprising ! LOL!

https://youtu.be/3SuYh3re12s

Kind regards.

steamboatmodel · « **Reply #1 on:** September 14, 2020, 01:25:49 am »

I have seen Maudslay gear with five or six gears, If Gears had been cheaper to make this type of gear would have been much more popular. I had done a set up board with Mechanio gear that demonstrated both sets, but unfortunately I loaned it out and it never returned, they had let there kids play with it and they lost the gears.
Gerald.

southsteyne2 · « **Reply #2 on:** September 14, 2020, 01:03:25 pm »

Many thanks KBIO for the information as I am at present scratch building a engine similar to the Cheddar Gemini with some modifications .will post some pics soon
Cheers
John

southsteyne2 · « **Reply #3 on:** September 17, 2020, 03:31:02 am »

Hi all found this video on the tube and the reversing gear appeared quite unusual ,has anyone built similar in model form? as I would be most interested.https://www.youtube.com/watch?v=6aUF4R_p0Vg
Cheers

John

southsteyne2 · « **Reply #4 on:** September 21, 2020, 12:54:20 am »

Sorry guys but if nobody wants to reply to my posts perhaps time to move on my sincere thanks to all the members that have helped me over the years .
Thanks
John.

steamboatmodel · « **Reply #5 on:** September 21, 2020, 01:31:07 am »

Hi John,
I have made one reply to this subject and had hoped for more information on the Maudsley Valve Gear.
Gerald.

derekwarner · « **Reply #6 on:** September 21, 2020, 01:41:53 am »

Morning John.......

I am not a Member but do [cook ?

] the Boiler Registrations Books for St.George MBC where you are a Member...could you not find any Member there to help with Maudsley?

Derek

southsteyne2 · « **Reply #7 on:** September 21, 2020, 02:01:58 am »

Hi Derek sadly our members interests in actual building model steam has diminished over the last few years due to age related or the access to cheap foreign imports feeding the need to more or less plug and play just to get on the water which to me takes away the romance of a bygone era. however to the video clip I attached all I wanted to know was this a type of Hackforth gear as I had not seen it before in a real working environment.
Cheers
John

DBS88 · « **Reply #8 on:** September 21, 2020, 08:30:29 am »

Thank you for sharing the link, that’s a fascinating insight to see the triple expansion engine working and what a lovely sound it makes. I enjoyed the video but as yet I do not know enough to be able to offer any opinion on the mechanism.

ooyah/2 · « **Reply #9 on:** September 21, 2020, 10:27:27 am »

Quote from: southsteyne2 on September 21, 2020, 02:01:58 am

Hi Derek sadly our members interests in actual building model steam has diminished over the last few years due to age related or the access to cheap foreign imports feeding the need to more or less plug and play just to get on the water which to me takes away the romance of a bygone era. however to the video clip I attached all I wanted to know was this a type of Hackforth gear as I had not seen it before in a real working environment.
Cheers
John

Hi John,
I am very sorry to hear that you are considering leaving the forum, over the years you have made a great contribution to the scratch building of model boats and the making of steam engines and boilers.
It's a fact that us Old `Guys are becoming less and less and you only need to look at the thread on gas and water pumps on the other thread to realise that people seam to be wanting as many electronic gizmos to fit to steam plants to allow them to let the boat go and sit on the bank and watch it sail it's self and to return when ever "IT" wanted to, I just can't see the pleasure in that.

Unfortunately the video link that you gave was not clear enough to see what type of reversing gear was on the Steam Tug

I have now been making boilers, steam engines and sailing them in a boat with only a sight glass, pressure gauge, safety valve and reliable gas supply and to daet never needed any thing else but the occasional bringing the boat into the side to inspect the water level and check that the pump is operating properly, these things are what I call learning to operate a model steam boat and all part of the pleasure of sailing a steam propelled model.
These in my opinion are all that is needed to learn how to operate a steam plant, I am sad to say that if the hobby survives steam plants will be operating themselves with all the gizmos that are available.

So John hopefully you will reconsider leaving and continue to subscribe.

George.

KBIO · « **Reply #10 on:** September 21, 2020, 10:57:56 am »

Ola my Friends !
Cheer up! We are the last (probably) in this smoky world but we enjoy to share our experience between each other thru the seas and the language barrier!
The experience is a lantern that the eldest are carrying on their shoulder to enlight the path for the youngest. Unfortunately the youngest are walking faster and pass over!

We sometime do not answer, waiting for someone more competent to do it. But Steamers are shy !
Ataboy ! We are a good, honest and friendly community, lets keep it this way.

Coming back on Southsteiyn2 question, I think that the reverse he is talking about is an Kackworth one. Largely used on trains but you can have a good exemple on Graham engine TRVR 1.
C[size=78%]concerning the Maudslay, I am not that I understood the question, but [/size]I[size=78%] gave a clumsy rough draft that I think explain the principle.[/size][size=78%]I modified my PB2 this week end and I am ready to share my (poor) experience [/size]with[size=78%] who [/size]needs[size=78%] it. I shall [/size]dismantle it after a quick breaking to smooth the gears teeth and fine tuning. (not a problem as it ca-n be done while the engine runs) .

Below is the work. If you have any question , please to do hesitate to ask! The only idiot in here is me and I can guarantee than I can survive well with this handicap!!

Thank you for watching.
Regards ;-)

steamboatmodel · « **Reply #11 on:** September 21, 2020, 04:12:03 pm »

KBIO
Very well done.
Gerald.

ballastanksian · « **Reply #12 on:** September 21, 2020, 04:18:47 pm »

In one way the fact that turbines do not work so well scaled down (from what I gather) means that if you want to build a model boat powered by steam, then its reciprocating or nowt. A gentleman did build a model of Dreadnought some years ago and fitted dental drill airmotors to use as steam turbines, but they needed far greater pressure. A true steam plant even at scale is a thing of beauty. Lovely work chaps

KNO3 · « **Reply #13 on:** October 04, 2020, 10:36:09 am »

Quote from: southsteyne2 on September 17, 2020, 03:31:02 am

Hi all found this video on the tube and the reversing gear appeared quite unusual ,has anyone built similar in model form? as I would be most interested.https://www.youtube.com/watch?v=6aUF4R_p0Vg
Cheers

John

The tug's engine uses Hackhorth gear. Graham uses the same on the TVR1A model steam engine, only with some added links due to the valves being positioned at the ends of the engine, not at a side as on this tugboat.
More info here:
https://en.m.wikipedia.org/wiki/Hackworth_valve_gear

KNO3 · « **Reply #14 on:** October 04, 2020, 10:38:10 am »

Quote from: KBIO on September 21, 2020, 10:57:56 am

Ola my Friends !
Cheer up! We are the last (probably) in this smoky world but we enjoy to share our experience between each other thru the seas and the language barrier!
The experience is a lantern that the eldest are carrying on their shoulder to enlight the path for the youngest. Unfortunately the youngest are walking faster and pass over!
We sometime do not answer, waiting for someone more competent to do it. But Steamers are shy !
Ataboy ! We are a good, honest and friendly community, lets keep it this way.

Coming back on Southsteiyn2 question, I think that the reverse he is talking about is an Kackworth one. Largely used on trains but you can have a good exemple on Graham engine TRVR 1.
C[size=78%]concerning the Maudslay, I am not that I understood the question, but [/size]I[size=78%] gave a clumsy rough draft that I think explain the principle.[/size][size=78%]I modified my PB2 this week end and I am ready to share my (poor) experience [/size]with[size=78%] who [/size]needs[size=78%] it. I shall [/size]dismantle it after a quick breaking to smooth the gears teeth and fine tuning. (not a problem as it ca-n be done while the engine runs) .

Below is the work. If you have any question , please to do hesitate to ask! The only idiot in here is me and I can guarantee than I can survive well with this handicap!!

Thank you for watching.
Regards ;-)

Hello, I see you have built your own Maudslay gear. Congratulations! Do you have a video?

KBIO · « **Reply #15 on:** October 04, 2020, 03:24:00 pm »

Hello KNO3!
No I do not have a video.
I had to dismantle the Assy as I have a stiff point . It runs well one way but it is a bit hard the other one.
I need to change the plates as the gears are too close from each others and the teeth are too tight. I need to spread them by 2/100 mm more to allow some play in between.
i'l get it done some time this winter.
Regards.

KNO3 · « **Reply #16 on:** October 04, 2020, 08:35:00 pm »

I like your set up, the parts are nice and small.
D I see correctly that you have built in two screws to limit the movement of the lever?
What are the rules for meshing gear teeth / distance?

KBIO · « **Reply #17 on:** October 05, 2020, 09:55:27 am »

Hello!
Yes, the laterals screws are there to limit the course of the lever.
As I said higher, it is for an accurate adjustment of 45° to allow the right timing of the sliding sleeves .

Concerning the gears distance, the book says that the right one is twice the diameter divided by two.
That is what did, but unless having a good break-in (and for how long?) , I find them sticking too much to each others.
So I'll try:
(2D x 2) + 2/10 th of a mm.
2
The teeth should be loose enough to allow a proper rotation without sticking and vibrations.
I'll let you know if there is some improvement , when I have it done!!

Regards.

steamboatmodel · « **Reply #18 on:** October 05, 2020, 03:05:17 pm »

Quote from: KBIO on October 05, 2020, 09:55:27 am

Hello!
Yes, the laterals screws are there to limit the course of the lever.
As I said higher, it is for an accurate adjustment of 45° to allow the right timing of the sliding sleeves .

Concerning the gears distance, the book says that the right one is twice the diameter divided by two.
That is what did, but unless having a good break-in (and for how long?) , I find them sticking too much to each others.
So I'll try:
(2D x 2) + 2/10 th of a mm.
2
The teeth should be loose enough to allow a proper rotation without sticking and vibrations.
I'll let you know if there is some improvement , when I have it done!!

Regards.

Hi Dave,
You said "[size=78%]Concerning the gears distance, the book says that the right one is twice the diameter divided by two." Which Book?[/size]
[/size][size=78%]Gerald.[/size]

KBIO · « **Reply #19 on:** October 05, 2020, 03:59:45 pm »

Hello SteamboatmodelI

HelloI
I see what you mean!
My explanation is wrong as if I have two gears of 12mm each = 24 mm and if I divide by two , the teeth won’t touch each other.
I should have write as the formula I found :
The normal center distance between two toothed wheels is the sum of the two pitch diameter divided by 2.
Pitch diameter =modulus x number of teeth (d=m.z)

The pitch diameter being the « Diametre primitif » on my drawing.

What I simply did is to engage the two gears together and measure the distance between the wheels center. . That’s tight but should works easy after some breaking.…….but it is easier and faster if I add some clearance. The thickness of a standard paper leaf should be enough.
Thanks for the remark ! I hope that I am not wrong now and any clear explanation will be welcome..
Regards.

southsteyne2 · « **Reply #20 on:** October 06, 2020, 12:25:58 am »

Make sure the gears are perfectly round as I bought some on the bay that were slightly out of round causing them to bind.
Cheers
John

steamboatmodel · « **Reply #21 on:** October 06, 2020, 03:23:00 pm »

Quote from: KBIO on October 05, 2020, 03:59:45 pm

Hello SteamboatmodelI

HelloI
I see what you mean!
My explanation is wrong as if I have two gears of 12mm each = 24 mm and if I divide by two , the teeth won’t touch each other.
I should have write as the formula I found :
The normal center distance between two toothed wheels is the sum of the two pitch diameter divided by 2.
Pitch diameter =modulus x number of teeth (d=m.z)

The pitch diameter being the « Diametre primitif » on my drawing.

What I simply did is to engage the two gears together and measure the distance between the wheels center. . That’s tight but should works easy after some breaking.…….but it is easier and faster if I add some clearance. The thickness of a standard paper leaf should be enough.
Thanks for the remark ! I hope that I am not wrong now and any clear explanation will be welcome..
Regards.

Which Book did you find this in?
Gerald.

KBIO · « **Reply #22 on:** October 07, 2020, 03:49:08 pm »

Hello Steamboat model.
Type "distance between dented wheels" on the net and you'll have a flow of informations on it.

Any engineer book on dented wheels will give you all the infos that you need.
Wikipédia is also a good help. That's where I had mine.
Kind regards.

steamboatmodel · « **Reply #23 on:** October 07, 2020, 05:11:04 pm »

When I search "distance between dented wheels" I find all kinds of information on dented car rims. I had been hoping that you had found a book about Maudslay Valve Gear.
Gerald.

KBIO · « **Reply #24 on:** October 07, 2020, 06:39:05 pm »

Good evening.
Gear technology and Maudslay reverse are totally different. I found out when I looked for proper gears adjustment.

As astonishing as it is , I did not find no documentation on Maudslay either.
Fortunately , after a long time scratching our head to understand the principle and some discussion to find a volunteer to work it out, one of our engineers of our Forum : "Rookie" , a very good pedagogue, wrote a very smart paper to describe the principle of the Maudslay.
You can have it here :

http://modelismenavalvapeur.forumactif.com/t832-distribution-systeme-maudslay-la-theorie-complete?highlight=maudslay

That's probably the only paper , you'll find on it. But if someone can find another one, it would be greatly appreciated.
I understand that it can be a problem for non French speaking people, but the drawings are clear enough and Google translation will do the job.

Hope you find what you need and that answers you question.

Thanks for your interest.
Regards.

Note. My small video helps to understand the basic , after it is just a question of machining down the proper Assy...... and get the right distance between two wheels centers !

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Author Topic: Principle of The Maudslay. (Read 3879 times)