Steam donkey? The full-sized single drum American Hoist & Derrick units I've seen have no clutch. A single lever runs the whole thing. When the lever is centered the engine is stopped with band brake on one of the crank discs is automatically applied. Pull the lever towards you, and the engine runs one direction, push the lever the other and the steam ports are reversed (like on a Ruby...others sometimes had a link reverse) and the engine runs the other way. The throttle is linked to the lever so that further you move it off center the faster the engine runs.... a second valve (globe) is often used on the steam line as a shut off and/or to limit the throttle. Many had a foot brake (band type) for the drum as well (in case the engine failed?)
Multi-drum units usually had a simple sliding pinion arrangement to engage/disengage each winding drum to the main shaft, and a seperate brake for each drum.
This one seems to show a unit with what could be a clutch? (the lever in the center of the axle) But I assume it is a jam brake. It engages using a coarse screw
BTW William Harris published a series of articles on building a steam donkey(with drawings) in Live Steam magazine years ago. It is available in book form. Try Nation Builder Books, Tony is a good guy.
For over a year I've been surfing to find the very details you posted. I never knew the 'pinion clutch' by that name, and couldn't figure out how the drums were clutched. I asked a couple of ME's I know, they didn't know what I was talking about.
Nobody knew. I bought the book you mentioned. It was vague.
I would like to clarify a couple details about the operation of steam donkeys. I am in a unique position to comment because I have run one. Not a full size donkey but the working 1:20.3 live steam donkey I built with a couple friends. We actually built four donkeys. I will not attempt to discuss all types of donkey but only the type that we built which is arguably the most common type of donkey engine. The design we chose was known as a "Two Drum, Wide Face, Road Engine" This type as the name implies has two spools on which the rope is wound. Our models were based on an American Hoist And Derrick design. The actual full size machine that we modeled is on display in Fisherman's Wharf in San Francisco CA.
Mik's theory on the use of the brakes is not quite correct. The brakes were actually used in the normal operation of the machine. The steam engine was non reversing and gravity is what unspooled the rope from the drum. When we load logs with our donkeys the engine is used only in the act of hoisting upwards or "spooling in" lowering the load (such as lowering a log onto a log car is accomplished strictly by managing the brake. These donkeys did have a safety feature to arrest rapid unspooling of the drum. This mechanism was a ratchet type. For ease of operation we decided to eliminate the ratchet and only install brakes on our models. Each drum has a brake and a clutch. On the real machine the brake was applied (as in a car) by depressing a pedal. On our machine the brake default is ON and you depress the pedal to release it. This is our way of preventing accidental unspooling. It works quite well for a model. For craftsmen seriously interested in making working donkeys we have several pages of drawings available for free download. We also created a 3-D CAD model of the donkey for reference.
If you need further reference there is a fantastic book on the subject called "In Search of Steam Donkeys".
Here you can see the two clutch levers and the brake pedals The throttle lever is also shown. The throttle has two handles so that an operator could reach it while working either drum .
Here is the 3-D CAD model.
Here is our team of donkeys in varying stages of completion.
If you are interested in downloading any of the drawings please go to this link:
For what it's worth, the "Donkeys" on the German guys site are not really donkeys. They are portable steam engines, because they do not have winches. There is only one machine shown on his site that has a winch and it is belt driven which is not, in any way, prototypicaly correct. I am also puzzled why there is a gap between the cone shaped smoke boxes and the top of the boiler. His creations while nice seem more like caricatures than models to me.
Okay, I yield to an authority, I guess maybe the one at the Portersville showgrounds, the one that was shown at Saegertown a few years back, and the FIVE (3 singles and 2 triple drum of the 10'x 12" variety) on the Crane Brother's crane barge COULD have been anomalies.... -- Or maybe those used for other purposes than logging might be set up to work differently.
Thanks for the data and pics! I find the donkeys fascinating pieces, and a live steam version irresistable. I just ordered an engine to assemble -no boiler yet-from Graham Industries. If anyone is interested, their engines are machined and only require assembly. I find their prices to be about the lowest around. And, they didn't charge shipping! $119 for a single cylinder, with reversing lever. Cheaper than some that are castings requiring machining. I think most cylinders would require a 4 jawed lathe. The pics/explanation will assist in the winch.
No problem! By the way Mik, I wasn't trying to attack you because I am hardly a real authority, but we did thoroughly examine a triple drum model in Santa Cruz and the two drum in in San Francisco and those ones operate in the way I described. There was also a series in Live Steam magazine written by the late Bill Harris on building a 1:8 scale steam donkey and his also operates in the way I described. All of these are "wide face" or "wide drum" engines. I could imagine that single drum models and narrow drum versions might operate differently. I'm not sure because I haven't done the research on those types. Bill, good luck with the Graham engine-- I have two of those myself!
Wasn't insulted, or feeling attacked. Always good to learn something new.
BTW, the single drum hoists at Crane Brothers were originally off a Liberty Ship. Sadly, they were damaged in a flood after removal from the barge and scrapped before our club could arrange to have them transported for preservation.
I don't doubt your take on the existence of friction bands. But the pics I saw had what's called a 'pinion clutch', of which I've seen several in use over the years. I know from that book that's been recommended, I have it, and it's vague right where this discussion is centered. I also think I can see the clutch handles in the blowup of the parts ID, they are not labelled, a not-uncommon failure with books on technical articles written by non-techs, or non-users.
In MHO, that book is good for an overview, but far from being technical enough to build a donkey, save as a freelance job. I'd recommend it, however, just for the overview of the subject.
Also, I think someone just above referred to the pinion clutch as a 'jam brake'. If we're talking of the same part, that's technically incorrect. Also, from some practical experience with 'band-type' power transfer, there's the risk of slippage/catastrophic failure, esp. if the band lets go. The pinion-clutches are positive-lock systems OTOH.
And the other gentleman is right: there is no power outfeed, they used a second line w. block & tackle to drag the cable back to the site where the downed trees were. I think that's what the second drum was used for. That may be covered in the book; not sure where I picked up that piece of info.
Like I said, probably different features for different uses... A hoisting engine vs a cable logging engine would LOOK alike until you studied them closer. The one at Portersville HAS a link reverse, and band brakes both on the drum (the one that is there, the second one is long gone) and one crank disc. The 3 hoist engines on the barge crane had piston valves and reversed via switching the ports like a Soule sawmill carriage engine. They also had band brakes on the hoisting drum
Ah! I found it. Bill Harris's Live steam articles have been compiled into some books. Many may know him for his articles/book on the cute little logging engine with a gypsy winch on the front known as the Falk. His articles on the steam donkey have been compiled into a complete book. I seems as though this book is still in print so it is pretty cheap right now. 15 bucks! have a look at ebay item number: 120368570839. Les is correct, "In Search of Steam Donkeys", while a great photo reference, and it even has a couple drawings, it will still not give you the technical knowledge to build a working mechanism. Bill Harris's book will.
The machine in Bill's book shows the type that I am familiar with, that has a friction band style brake, clutch and safety ratchet on both drums and a non reversing engine.
Les, your description regarding clutches is correct. What I was trying to describe, but may not have been clear earlier, was that we changed the mechanisms to work better in 1:20.3 scale. We ARE using friction band brakes, but ours are default ON. Our machines do not have the safety ratchet (because if a 1:20.3 scale log gets away from us, it wont kill anybody) and our clutch mechanism is not a pinion type, but instead a pressure plate-- again because catastrophic failure or slippage do not pose a safety hazard in our scale. These were just some small compromises for a working model. this allows us to capture the look of a full size machine, we can also accomplish the same task but have a simpler operation.
I think I got the gist of your explanation the first time around. I have no problem with deviations from an original design so long as they're duly noted. In your case with the brakes, I can't see a thing to be feared from accident, or from using a clutch plate in place of pinion clutches. Sometimes I think the 'hazard' bit gets 'way overdone.
For those who thought I was nutz or making stuff up -- I finally got pix to prove I wasn't (at least not on this). Stephenson's reverse gear, brake, throttle -- ONE lever does it all. (American Hoist & Derrick, with 4-1/2 x 6 cylinders... but what was it made for?)