Upping the gearing?

Has anyone tried or is it possible to up the gearing on this model. I spend most if the time in high wheel with the 3" and don't expect to be using low on the 4". I intend road registering the engine when complete and think that a higher gear for the road would be good. Is there room to change the ratio on the final drive pair of gears?

It's an agricultural engine & not a road loco, it can clip along at quite a reasonable rate on a smooth road. With a scale model one looks for a scale speed & I would say it surpasses that anyway if pushed.

Been playing around with the gearing myself, engine is not fully complete yet but I can see what you mean. You can of course argue that is not a road loco and should not be expected to go that fast, but then neither is it a "real" engine.... I have the CAD done for some new gearing but have not cut any metal yet. I was also thinking of doing a lower geared set, something which maybe of use for doing some hard work  If you can do these things, why not  

So which gears have you found to be the best to change, final drive or high and low wheels? What sort of change in ratio have you acheived? I was considering cutting a new set of final drive gears on the wire edm at work.

The standard gears do everything you could possibly want from the engine, earlier this year I pulled a Ford Maverick (1.7 tons) around a sloping ring at Boconnoc with little difficulty in low gear. In high wheel it nips along quite fast enough for chain steering and keeps up with 9 out of 10 other miniatures. It's faster than any full size roller so there are no issues with holding anyone up on the tracks at a rally.

And to be honest why fix something if it aint broke!???

Those southern based rally goers will no doubt be familiar with one particular steamer who seems to think he is in an XR3i and drives about like a total prat and has almost caused the closure of several events due to "careless and dangerous" driving. It is much more impressive to drive at almost no speed at all barely adjusting the regulator to maintain a steady pace, these are after all steam traction engines not express trains.

I have had a 4" agricultural and will confirm Steves comment, 2nd is more than adequate for chain steering and no brakes and keeps up on a road run and a more impressive display is to pull as much as you can in first.

Is high wheel gearing similar on the single and the compound then?

The RL/Showmans is a three speed and much more powerfull. High wheel will be faster however that will only be useable on smooth surfaces. With no suspension and solid tyres speed is relative! Also with the average rough, badly repaired roads we now have any excess speed has the habit of finding anything that you forgot to locktite. This isn't really a hobby for speed merchants.

I'm not looking to break the land speed record nor match the speed of those 6" scale Burrell Gold Medal Tractors that seem to motor. My only experience of steam is the 3" model I run which is far to slow and small for the road and was thinking I could make the 4" more useful on the road with higher gearing.

Try a season with the standard set up, I think you'll be quite happy with it. It's way faster than a three inch engine.

Watch out if you start adjusting the gearing or you may have trouble when registering with the DVLA for road use. Like Steve says I would leave it as standard and see how you get on.

Thought that post might get a reaction, but then it has been a bit slow on here lately. I do agree with what you guys are saying, I'm not looking to drive an engine so fast i'm not in control or that i'm classed as"reckless" by others. However being an engineer I have a natural urge to change and develop things to either improve basic function or performance. We all know these engines have plenty of power, but at the top end of the "rev" range things tend to move a bit quick for a simple engine design. By changing the drive gearing will allow you to reduce that engine speed, (keeping vibrations and speed to a minimum) and make better use of that low down torque these engines have. On the flip side i'm am also interested in changing the lower gear to see just how much pulling capability one of these little engines can have and give it a distinct difference in performance to that of the standard engine.

Also with comments like "if it aint broke dont fix it" while I respect the personal views of others, if we all took that line we would still be walking to work and using horses as our primary source of power! This is more of an experiment than anything, and to be honest because I can......

Running out of grip / front end lift limits pulling power rather than gearing. Why not fit spuds to the wheels (there was a variation designed for rubbered wheels)

Slowing down very much relies on engine braking. Running in a high gear will noticeably reduce this. I have often wondered if a drum brake could be hidden inside the winding drum.

On the agricultural the engine will hold back as a brake quite well. On the RL in high wheel it doesn't and you need to use the rear wheel brakes. The band brake on the agriculture is quite good, but I wouldn't want to be using it too much. Being able to stop is far more important than going fast, and believe me, when things go wrong it happens fast!

Tim

I fitted a Halfords bicycle speedometer to my 4" so I could see how far I went, as much as how fast I went. Rolling along at 3-4mph is comfortable. The engine revs, in high gear, sound fine and the steering is controllable (I have fitted a tensioner in the steering chain which reduces the "slack"). Increasing the speed to 6 mph and look out, every bump in the road means you have to really concentrate on the steering and "things" can happen quite quickly. Besides that, you start using up steam and fire at an unsustainable rate. So in many respects the standard gearing is set just right, a good balance between power and speed, and as Tim has said can provide a reasonable amount of engine braking when required.

I have the same computer on mine and for a comparison I have covered 74 actual miles with a top speed of 11 mph which was pretty terrifying!! In third at mid revs it runs about 6-7 which is comfy. In the aisles on a rally field it doesnt register the speed as it is below 3 but we normally use second for this.