|Dec 27, 2012, 02:25 PM|
New steam engine supplier
Three new engines actually- 2 from Typhoon and one from MH&B. We have been discussing this new entry into the steam engine world on the other steam forum I frequent ( Mamod and Other steam)..The manufacturer also posted in the SUPPLIERS sticky on this forum
They have a V twin and a nifty little single that is reversible in a simple but unique way
They have two videos
Also the renowned Steam Boat Kit maker Martin , Howes and Bayliss also has a new engine in the works.. We have been exploring it also here:
Here is the M, H & B site:
P.s. I have no connection to the Typhoon folks- I just was unsure if the participants here had noticed their post in the suppliers are
|Dec 30, 2012, 12:40 PM|
Looking at the video and photos of the single cylinder to determine it's unique reversing method:
1. I can't tell if the motor has a D-valve or a piston valve.
2. Either valve can be made to reverse. A piston valve can reverse if you change from inside admission to outside admission. A D-valve allows only outside admission; normally, a locomotive-style reversible D-valve requires 2 eccentrics, one for forward and one for reverse. However, you can get away with 1 eccentric if it's a "slip eccentric." Slip ecc's can rotate a set amount on the shaft; with a loco you just roll it along the track in the direction you want to go, then open the throttle. The rolling slips the ecc into the desired position. You can also get away with 1 ecc if you have an appropriate linkage (eg. Hackworth on the TVR1a) - I did not see linkages so won't talk about this method.
3. Even with reversal, a single cylinder engine can get stuck on top dead center, and other positions.
4. The photos presented on their website disguise the reversal method used. Perhaps the words explain, but in the absence of French lang. skills, I will guess.
4. Guess: 1) I think the motor uses D-valve, slip eccentric positioned by servo, and servo-repositioning of the crank to get motor off dead positions. The repositioning is clearly visible in the video.
Guess 2) The motor uses a piston valve and servo repositioning of the crank. Some Accucraft locos use piston valve inside/outside for reverse (since their locos have 2 cylinders, they don't have to worry about the crank).
Neat either way: The throttle handle serves double or triple duty, controlling both the direction of rotation and repositioning the crank, plus it's regular speed function.
5. The repositioning by servo adjustment idea could be used on other reversible single cyl. motors.
So, Mogo, how was my guess :-)
|Dec 30, 2012, 12:59 PM|
Wrong guess. The engine uses piston valves and reverses with a very usual disc reversing valve, as many other engines have. The new thing is the long lever of the reversing valve which also nudges the 2 pins placed at TDC and BDC on the flywheel.
|Dec 30, 2012, 01:44 PM|
You can barely see one of the pins at 12 seconds into the video--I marvelled the same when I first saw it Brooks..
I do hope you and your loved ones all had a Merry and a safe Christmas..the turkeys too!!
|Dec 30, 2012, 05:42 PM|
Kno3, thanks for the info. As a matter of clarification, the action of a disk valve + engine piston valve is to do as I stated, namely convert inside admission to outside admission. I have a steam launch that uses a disk valve to do this flip/flop. Accucraft uses a interestingly machined piston valve to accomplish this flip/flop of admission in the engine piston valves.
Piston valves on real US locos didn't flip/flop admission, but were re-timed via the 2 eccentrics (or their equivalent, via linkage, in a radial style gear). One reason was that the reversal of steam flow inherent in a flip/flop causes energy losses until the valve chest has adjusted to the new heat flow patterns. Loss of energy translates into condensation: a switch engine running back and forth would be spitting condensed water out the relief cocks all day.
How does the Typhoon motor keep the pins from hitting the throttle arm once motor starts? I suppose one way would be to run the arm past the pins. Inspired design would allow machining the disk to allow slow throttle action to occur once the arm had cleared the pins, perhaps?
|Jan 01, 2013, 05:13 AM|
Brooks, yes the disc valve swaps admission and exhaust. Quite common in model/toy engines, and I guess not encountered in full size engines, probably for the reasons you give.
As you say, the throttle arm clears the path of the pins as soon as it has pushed them into the desired direction. If the lever travel circle is made in such a way as to intersect the pin travel circle only at TDC it should be easy enough to keep it from colliding fourther down their path, which is only used for throttle action.
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