Advice on jerky running

Yep.

Ian J.

Reply to
Ian J.
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Sorry it was late, didnt mean coupled as in with coupling rods but all connected up with motor and gears. The additional stresses are what changes more or less ok to jerky. Strange but would really like to know if B2B same all way round on wobbly wheels - any chance ?

Cheers, Simon

Reply to
simon

I don't have a B2B gauge, but the measurement by ruler/eye looks about right.

Ian J.

Reply to
Ian J.

I used to use a bit of plastic cut to about right size - about right is fine as long as everything is consistent. But must admit when got a proper guage (L shaped, approx 3mm thick) it made an amazing difference to one or two locos. went from slight wobble of wheels to perfect with no wobble and loco was much smoother running. Cant say what tolerence required but 0.5mm differnce results in big wobble. Simon

Reply to
simon

Now I'm totally lost ;-)

Were the coupling rods in place when you did the freewheeling test? I presume that the drive-train from the motor wasn't!

John

Reply to
caronprom

Coupling rods have always been in place, motor hasn't. In the freewheel test the motor gears were removed, and wheels seemed ok (there was a very, very slight binding but I couldn't even figure out exactly where it was occuring.) With the motor and gears in place, but without the base plate of the chassis in place, there is a definite binding occuring at one point in the revolution of the wheels. That's why I feel that maybe the gears are contributing to the problem.

Anyhoo, the loco is generally running better now, so I am less bothered with it specifically at the moment as I have others to attend to. Many thanks for all the general advice to all who replied.

Ian J.

Reply to
Ian J.

Ian,

If your quartering is off then you can get the results you are getting. When the axles rotate with faulty quartering, then the chassis tries to get over the tight spots by using the play in the axle bearings and the crankpin bearings. You can see this when a chassis runs, and one or more axles tend to rock. When you engage the motor and gear, you restrict the free play on the driven axle and the out of quarter chassis has lost a bit of its elbow room and tends to bind more. You might find that it runs better if you pack the motor mount so that the gear mesh is very loose, which might let the axle move around a bit again.

Jim.

Reply to
Jim Guthrie

I suppose what has happened must have been a slight loss of true quarter when I took the chassis apart to install the decoder, but I did try to manually move the wheels on the axles and couldn't budge them, and I definitely didn't handle the wheel set roughly, quite the opposite in fact. Whatever happened, it looks likely that quartering will need adjusting to get a smooth runner again...

Ian J.

Reply to
Ian J.

Dont stop now, its excellent experience cos theres so many 'slightly out' locos that benefit. Theres almost as many causes. I realise its arkward as youve just chipped it, but if you can stand it upside down and apply continous power so that you can watch wheels, coupling rods and valve gear etc then sometimes its a lot easier to spot the problem.

Simon

Reply to
simon

Well, I did that, that was how I found that it was the gear meshing that seemed to be pushing the wheels to bind. This looks to be a quartering issue, as far as I can ascertain.

Ian J.

Reply to
Ian J.

I'm missing something here on quartering and would like to be re-assured or corrected. Having removed all the wheels on the average Hornby or Bachmann loco i then :- put 1st wheel on axle put axle onto chassis put other wheel on axle in approx posit set one side to 1200 look at other side - twist wheel on axle to 0300 (or 0900) look back at first side, reset it if not right look at other side - twist.....

and so on till happy theyre right. Then do other wheels to match.

Is this, in the teams opinion, just not good enough ?

Cheers, Simon

Reply to
simon

Er, why are you removing the wheels from the axles? Certainly on locos like the J39, there is no specific need to do this. On a loco such as this the three axles come out as a 'unit' - the coupling rods keeping them together.

Ian J.

Reply to
Ian J.

If it works for you then fine. Its usually easier to assemble the first wheelset before putting it in the chassis, then you can see both sides at once and get it right first time. Only if you have to deal with the very old chassis that don't have keeper plates do you have to assemble the wheelsets in the chassis as you describe. Keith

Reply to
Keith

Lots of reasons. well one or 2 such as on second hand loco thats been oiled from a tanker. Have to remove crankpin so may just remove wheel anyway. Nearly always remove coupling rods cos am ham fisted and dont want to bend them when cleaning wheels. With modern hornby its a devil to get the flat plastic sandwhich at base of chassis back on whilst keeping pickup strips in place. Easier to remove one wheel from axle.

Any advice suggesting better ways always welcome.

Cheers, Simon

Reply to
simon

true, I do do that if theyre fully out. Only described this way cos Ian's are (presumably) back in now and I wouldnt bother taking them out just for quartering.

Simon

Reply to
simon

I too use the visual method! Having set one pair, I then attach the conn rod to one side. I then hang the other conn rod to the chosen master pair and adjust the 3 rd pair until it fits nicely at its apogee ( having locked the datum pair with a clamp. The centre pair or pairs can then be set con rod hole to wheel pin hole using a paper clip as a probe and if necessary a magnifying glass to see it ( essential in my case. The paper clip can also be used to determine the centering of the second pair as with such small diameters the wrong position is quickly evident if the axle centres are used as an aid to alignment i.e. set the first wheel with its crank pin horizontal to the axle pin and aim the other in the same plane.

Reply to
peter abraham

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