Flat Belt vs. V Belt

Hi All, I recently acquired a Bamford EV4 and want to put it to work turning a screw cone log splitter.  The engine has two flat flywheels on a 1 3/8" (37.3mm) shaft and the screw has a V pulley on a 1 inch shaft.

I can either get a 38mm V pulley from machine mart or I can get a flat pulley with a 1" shaft.  So my question is which is better at transmitting power flat belt or V pulley  

For a log splitter I'd opt for a pair of Vee belts rather than a flat belt . I've found Vee belts perform better with high torque loads that aren't a constant "pull" a and also you will get less slippage on smaller pulleys than with flat belt.

Yes twin V belt as Villiers said for a screw cone splitter as if it go/s into the log half way and the belt slips you/l have a hell of a job getting it from there

No great experience but, at the risk of being shot down, I'd tend to go for a twin V pulley smaller, if possible, than the one on the splitter shaft. - reduced rpm but more torque.

Agreed Woodsman. You want the splitter going about a third the speed of the engine. That will give you approximately 3 times the torque of the engine, ideal for the knotted bits!

Thanks for the advice chaps, in the post to me is a 300mm diameter vee pulley, along with taper lock to fit the engine shaft and a big belt.  Going through my mind is safety, tension and torque, I have concerns about belt slip whilst splitting and being able to stop if there is a problem.

The pulley on the cone is about 200mm so it should spin a bit faster than the engine, this may be a mistake, but the pulleys are cheap, so I can buy different sizes and experiment, I'm hoping that bigger pulleys have more surface area on the belt so will reduce slip.

Once all the bits arrive step one will be to temporarily assemble to test everything.  Assuming it goes to plan, step two will be to build a rig to house the cone splitter, at the right working height, set up the right tension and build some safety into it.

Just a thought. Why not add a third, jockey, pulley into the equation. That way you can adjust tension in the belt and possibly disengage drive by letting the belt slip if there is a jam.

Having the splitter running so fast is probably going to be a problem, most are designed to be driven via a pto on a tractor and only need to turn slowly, one I use was doing about 250 rpm, slowing down the engine isn't going to work as you need the power, I've know a splitter stall a tractor and that ha more power than the Bamfords.
Bigger pulleys will help with belt wrap but with a Vee drive this isn't as important as with flat belts as you get grip from the sides of the Vee and not the pulley surface and the more load gets applied the more the belt gets pulled into the Vee thereby increasing grip.

Ok, so the big engine vee pulley arrived today, I've just got in from testing everything, bear in mind this a bench test so a real cobbling of bits, however I've learnt a lot.  Firstly you wise sages were correct I need less speed and more torque, will probably need a twin vee pulley set up,  with small on the engine and big on the screw.  Engine will need to run a faster than slow tick over speed to prevent stalling and I'll need to find a way to keep tension on the belt with a safety system which allows disengagement in case of a jam.

Yeah that ain't gonna work.
Twin or triple Vee and have a spring loaded pulley on the slack side.

Yes I agree with Villiers it ain't a over centre spring loaded tensioner on a lever on the slack side mounted near to the splitting screw so you can knock it out of gear if you have a blockage and that way the tension on the spring will decide when the belt slips or grips

You also need to make sure both the engine and splitter are well fixed down as if it snags it will snatch both together in no time.

Hi Guys .
I do not wish to be a know all .But the way you have that splitter set up you are going to hurt yourself or some one else and wreck your gear. What you are trying to do can be done .It has to be done by using counter shafts .That is small vee pulley on engine to larger pulley on shaft with another small pulley to a much larger one then your worm splitter . If it was mine I would be running through a dog clucth .I also feel two vee belts is not going to be enough more like 4 you are putting a lot of strain on two belts .I have spent many hours on one of those behind a tractor and seen a 70 hp tractor stalled with one of those screw splitters .They work and work well but you still have read your log just like splitting with an axe .
All the best with your project.
Maglad from NZ

Your advice is valuable so thank you all for taking the time to reply. I really want to keep the build simple, I'm thinking that being able to add tension to the belts with a adjustable tensioner is a good idea, but also allowing the belts to slip when overloaded allows the system to cope with any issues, so I'm minded not to go down the route of 3 or 4 belts for ultimate grip as this will move the failure point to another weak point.