Wooden trollies

I think its a camera induced bend. The timbers look more than adequate to me and I know Nev to be a craftsman. I would however entirely agree with your strictures on hardwoods. Most original trollies (where timber) I've seen are lovely Oregon Pine for which I suggest a decent bit of Douglas is as close as you'll get at a reasonable price. Sweet Chestnut is good if you can get your hands on some. Many large engines were on timber and small on steel and I can see no justification whatsoever for an arbitrary hp or weight limit. Certainly the necessary depth of timber for a large engine would tend to make the ensemble rather tall. OTOH timber is rather better at damping out vibration than steel. Steel trolleys with rubber wheels is a combination rather prone to leaping about :-) Further what makes you think that those with little or no grasp of rudimentary stress calculations for timber have any better grasp for steel? I'd also suggest that even an ill-fitting mortice joint has more structural integrity than a few gobs of pigeon-dung.

regards Roland

Work it out

Of course the timber is "sagging". The only question is how much.

Steel will sag too. It won't do as much sagging for the same size of beam, but the sag-per-trolley-weight won't be so far off it.

Andy,

The 'sagulator' is a wonderfully useful device but it calculated the 'sag' on my 5 HP Petter M trolley at 0.05". Undoubtedly fine for the static load but found somewhat wanting when applied to the same load doing 650 rpm with slightly unbalanced flywheels or when being driven over sleeping policemen! Having shuddered at the sight of it running at the last rally, I swore that it wasn't going to see the light of day again until a decent I-beam or channel section steel trolley had been built! (2 off, red pine runners 4" x

3", mounted the wrong way up!).

Mark

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I'm inclined to agree - it's the grain in the wood (if it's not scumbled) that give the appearance of "bent" wood.

I've got a couple of pieces of 150-year-old wooden joists which I think may be Red Deal - I'm going to use one of these, cut in half lengthways, to mount my Lister D on.

Brian L Dominic

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Roland,

My weldings not that bad :-))

What about that Lister L near us at Burford, he kept filling his water tank not because of heat but because the wheels were so far apart the water was bouncing out of the top of the tank.

Martin P

Douglas is cheap at present (Bristol anyway) - I was quoted £12 / cubic foot just a week or two ago, same as larch.

Southern yellow pine is easy to find and would do well, for a moderate price at the high end of softwoods.

Why sweet chestnut ? I've only a little experience with it, but IMHE it's nasty splitty stuff and rather brittle. Good rot resistance though.

You may be right about the unsuitability of oak loaded in shear, Kim, but my gut instincts don't go along with you.

The original wooden trolleys in my possession are of oak (Lister Junior) and pitch pine (Bamford Horizontal). The late Richard Bamford confirmed to me that Bamfords used Pitch Pine by preference for their trolleys.

Living in a house whose roof is supported by oak purlins loaded in shear and with upper floors supported by oak beams and joists, similarly shear loaded, perhaps I should be concerned, but I sniff at this peril :-).

Oak has been used as structural wood for a very long time now, and boat builders were quite keen on it.

I don't see a lot of timber framed houses in ash, though admittedly ash is less durable. Surely the reason ash is used in some engineering circumstances is because of its good tensile strength for its weight, while oak is more dense and therefore not ideal to make a Morgan from....

Regards, Arthur G

No doubt your roof was put up green, Arthur, thus it shrinks together & locks up nicely as we are finding with the Longhall, a building entirely constructed of oak. The other thing to consider is the loading per square foot - we did our sums & found that in copying extant structures we had wildly over engineered the roof, something which gives us a nice warm feeling when the stormy winds do blow!

Roofs are cross braced with trenched & clenched purlins, then stabilised with batten & stiffened with tile or slate. Carvel built ships are braced within an inch of their life by ribs and with grown knees of all kinds.

Trolley timbers are not usually triangulated, cross braced or otherwise supported, most are simply mortised & tenoned together at best and if the joint is not a light drive fit, then it will "work". It seems to me that the crankcase or base is supplying rather more towards structural integrity than the maker intended, which is my real cause of concern as the improperly-supported casting will crack eventually & that's another engine gone :o(( My other bet noir is the "stacking" system of timber trolley construction where the engine ends up perched on a coach-bolted criss-crossed pile of wood looking very precarious!

I entirely agree about Douglas Fir & Pitch Pine being a good timber in this context - so long as the sections are sufficiently large. I too have found chestnut both sweet & sour to be fine for floorboards and stair treads & risers if carefully dried in the log, but I'd not put my trust in it as a structural timber.

How stands the forum on aluminium channel section as a basis for motivating later engines?

regards,

Kim Siddorn.

Aluminium has two tiny reasons for not being used as a trolley, in structual or engineering use it is also stiffened in some way. My two reasons for not using it is age hardening rendering it brittle and its ability to corode and turn to powder. Also welding it is an art form so building a trolley would use lots of bolts and rivets.

Martin P

I concur and would only use Alu where the original did. As an experiment I ran an 8hp M today on the crap trolley that it came on. Plainly 4 x 4 is inadequate for 1/2 ton/8hp :-) Zebedee.......... Even a 5hp Petter uses 5 x 4 which for a 6hp Atomic is greatly braced by steel angle and plate. Even then Petter moved swiftly to steel for the Atomic. May I propose a simple solution that does not embody any generalisations and suits my purist streak: do some research and reproduce the original..........now there's an idea ;-) ttfn Roland

The grain gives the illusion of a bend probably. Might have been better to orient the timber so that the curvature of the grain was uppermost, as in heavy goods trailers which are built with an upward curve so that when loaded they are close to 'flat'. Lots of nice salvageable first growth Douglas Fir out here in BC. Surely the UK abounds in first class old timbers that could be salvaged and re-milled?

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If only. The good stuff goes for architectural salvage and its a job to find anyone who wants to risk their machines on re-milling. ttfn Roland

You are assuming that the factory got things right of course. When a large engine is bolted down it generally sits on a concrete bed. It's shimmed into alignment and grout is poured round and under the base. The bolts are only tightened when the grout has set. This effectively moulds the base to the engine so avoiding introducing any stress when the mountings are tightened. Now a trolley is a different matter. It's very unlikely to match the engine base perfectly and if it's rigid, tightening the mountings will introduce stresses. If the trolley is flexible though, it can flex to meet the engine. Of course, the clever bit is making it flex enough where it matters and not where it shouldn't. The fact that the trolley is then expected to sit on an uneven field adds another dimension. The field should not induce stresses in the engine. So we need a trolley that's flexible to the engine and rigid to the field. I see a two part trolley design if we're not careful. The technique normally adopted is a rigid trolley and "soft" mountings for the engine. Then again, the thought of a stationary engine leaping along at an event with the owner in hot pursuit is quite amusing. Perhaps it could get around my one real disappointment in rallying SE's, we don't get to parade around the ring even if our engines are small enough to carry (just).

John

I assume nothing. Most engines that make it onto the rally field without a lorry were also available in "portable" form, the design of which either stood the test of time or was speedily revised.

ttfn Roland

Mark mail direct to you is bouncing. I'll send the desired info next week once I dry out after Welland :-( regards Roland

Had this back tonight in response to an email I sent to this poster:

"Hi Peter. Thanks for writing, but unfortunately I'm not Rob. He appears to be using my email address. If you contact him, would you please ask him not to? Ta a bunch. :-) Best regards, S. R. Burnett"

Peter

"Roland Craven" wrote (snip):-

Why so glum?

If you can't see the Malverns it's raining...if you can see the Malverns it's going to rain..... Currently trying to decide whether its worth risking taking the 5 hp appletop. After its tantrums at 1000 Engine, I've got it running quite well on a borrowed magneto of dubious vintage, the bearings being dog rough. The big question is will it last for three damp days of fun :-) Don't want to take the S type as they're going to be well represented, and with it being wet underfoot, and knowing the site, I don't think the 8 hp Atomic would be a good idea :-)

Regards

Philip T-E

"philipte" wrote (snip):-

Only been once before - last year when weather was fine. Is it one of those sites requiring sturdy footwear if it has been rained on at any time during the previous week?