Re: Why is quartering a necessity?

Lionel's models of the "General" 4-4-0 all have the side rods at 0 degrees. It's actually a very smooth drivetrain, but of course all the rods & gear are just following gear-driven wheelsets. It was done this way due to the design of the smoke unit actuation. As you only see one side at a time running under normal circumstances, I never noticed this until I had one in a foam cradle for service and the power on!

Quartering is extremely important if the rods are actually transmitting power in the model - like the popular postwar Lionel Steam Turbines and Berkshires with the single worm drive. The electric motor drives the rearmost axle & drivers, the rods carry the power to the next three axles & wheel sets. Needles to say, lubricating the side gear is also an important aspect of maintaining these locos.

The vast majority of Lionel steamers were/are spur gear driven designs, but all (except the Generals) were assembled perfectly quartered, with the right side 90 degrees ahead of the left.

Rob

Nigel: good analogy with the bicycle.

Actually it's not. Two pistons connected to a crankshaft 180 degrees apart are just as bad as two connected at 0 degrees apart. Pushing or pulling on the crank shaft at either top dead center or bottom dead center is applying the piston force directly through the line of the crankshaft bearings and will not result in rotary motion of the crankshaft. As a kid, I used to enjoy seeing how long I could be extra tall by balancing and standing up on the upper bike pedal when it was at the 12:00 position on the stationary bike. Gary Q

Quartering is not just putting the siderods 90 degrees relative to each other on the axle but getting them all exactly the same angle. The angle is needed because the pistons can only push and pull on the drivers. This means that the only time that the maximum force can be applied to the drivers is when the angle on the driver to the pin that the piston pushes on is at 90 degrees to the piston. Other angles produce less power to the tire and that power goes to 0 when the pin on the driver is exactly in line with the axle to the piston. If you didn't have quartering, the loco could stop at this point and never be able to move again until something else moves it off of that postion. With quartering, if one side gets into this exact position, the other side of the loco will be in exactly the opposite condition where the siderods would be able to transmit the full power of the piston to the tires and thus provide a good driving force for the loco.

-- Why isn't there an Ozone Hole at the NORTH Pole?

are just as bad as two connected at 0 degrees apart. ...

Excellent point, Gary. I didn't mean to imply that a bicycle is just like quartering, rather that Nigel's post mentions a similar concept that most people are familiar with. Your description and others do explain the more technical aspects.

This topic comes up frequently.

Depending on how one interprets your statement, you are likely correct. The important thing is that the wheels on the two sides of the loco must all have the **SAME** phase angle with respect to one another. Typically this is 90 degrees, thus the term 'quartering'. But any angle near 90 degrees will work, say 70-110 degrees. 90 degrees works BEST, however.

The mechanism won't work at all if the angle approaches zero degrees, or

A two cylinder loco with double acting cylinders thus produces four power impulses per revolution of the drives ... heard as 'chuffs', each

If a third set of cranks is included, as on a 3-cylinder loco, or a

Dan Mitchell ============

While this certainly true, it's only part of the problem. Even without cylinders at all, as in a model with one geared axle, rods set anywhere near 0 degrees, or 180 degrees, will not work as they cannot impart rotational forces between adjoining driver sets.

The use of stiff (one piece) siderods on a three or more driven axle loco will somewhat lessen the lock-up effect as the multiple wheels will TRY to stay in phase, but unless all the clearances and tolerances are held VERY close (far better than most models), locking will likely still occur.

With (usually correct) multi-segment jointed siderods, angles near 0 or

Some model steam locos (mostly European made) gear all the drivers together ... this removes the driving forces from the rods, (which are then purely decorative) and makes this discussion inapplicable. any angle will then work, but may not be prototypical at all.

Dan Mitchell ============

Dan Mitchell ============

It will make a BIG difference to a model loco. At zero or 180 degrees, or anywhere near these values, the whole mechanism will lock up. This assumes jointed siderods, and NO gearing between axles, which is the usual case with USA made model steam locos. The angle SHOULD normally be

Dan Mitchell ============

That is why 90 degree V-8 motors were easy and popular to build, also why Harley Davidson motorcycles have their disyinctive sound.

Bob

Actually, 90 deg. engines are more an easily balanced setup, when used in the larger counts of pistons. The Harley design is just poor design work more than anything else.

-- Why isn't there an Ozone Hole at the NORTH Pole?

Thanks for clearing that up. My point was, though, that all wheels have to have the same degree setting. Since 90 degrees was used, it should be that, of course.

Some (all?) 3 cylinder simple locos used 120 degrees setting.

True, true, but we have (if you follow the gist of the thread) been discussing 2 cylinder locos.

On another thread dealing with steam sound, mention has been made of some British three cylinder locos being slightly off 120-120-120, though.

Well, there's a small degree of confusion around three cylinder locos. You should find that the wheels and the outer cylindercranks s are 120 degrees apart, and the center cylinder is moved upwards to clear whatever odds and ends the designer inadvertently left lying around in the front part of the frames. The odd unevenness of sound comes from incorrect valve timing, not from the uneven angle between cylinders.

Regards, Greg.P.

Brian,

That was usually because the inside third cyllinder was inclined at a different angle to the outside cylinders since it normally had to be placed a bit higher to allow clearance over bogies and leading driving axles. So you could get something like120-119-121.

Jim

Some also had the drivers quartered, with the third cylinder at 135 deg. between them. I think there would be an advantage to this arrangement, since the third cylinder, as far as I know and can guess, did not mean there was a third set of side (coupling) rods fitted.

In a quick skim of an article on conjugate valve gears I saw mention of Gresley's K3 2-6-0s of 1920 having crankpins at angles of 127-113-120.

Clearly, that third cylinder complicated things.

I knew there would be an exception! The result of the 90 deg plus 135 deg setting would be that the two outer cylinders would act just like an ordinary two cylinder loco (four evenly spaced chuffs) and that third cylinder would chime in two more chuffs between two of them. (chuff-chuffchuffchuff-chuffchuff ... per revolution)

Not really, if you angle the cylinder and crank the same amount you get even strokes at even intervals. The intervals are still as if the cylinders were in line at 120 degree intervals. With the derived third cylinder valve timing, the strokes have to be at equal spacings. The unequalness occured because all the pins and bearings deriving the center cylinder valve timing wore and caused the timing to be delayed.

Regards, Greg.P.

You've said this before, but it is mechanically impossible.

Think of it like a clock with the cylinder to its left.

If the cranks are angled at 12 o'clock, 4 o'clock and 8 o'clock the pistons would "fire" at 12 and 6 o'clock, 4 and 10 o'clock, and 8 and

But move one crank out to eg 4.30, then the piston has to "fire" at

Mechanically the rightmost position of the piston in the cylinder cannot be at 4 o'clock and the crank be at 4.30.

All the three cylinder locos I heard went:

chuff-chuff chuff-chuff- chuff chuff.

The irregular beat was NOT caused by the vales being improperly timed....just like as Shay sounding difference since there are so many cylder exhausts per wheel revolution.

The thngs were a disaster to maintain due to the difficulty of getting to the main rod and valve of the center cylinder. Many railraods (like the Lehigh valley canverted them to 2 cylinders.