Chassis Problems

[Saveric74]

Dear All,

 

i am currently building one of Jim Mcgeown O gauge kits (the drewry loco) and i have managed to get the chassis to roll forwards very smoothly when i push it along, but when i try the same in reverse the motions seize up.  Any ideas what it might be please?

 

best wishes,

saveric 

[hallmodelspares]

Is the motion locking? it could be the quartering is out slightly or if axle has no oil/lubricant it will bind up

[Saveric74]

Thanks for the reply.  The motion is locking.  It works fine as an 0-4-0 in both directions, but when the coupling rods that connect the rear wheel to the Flycrank are added then it binds up in reverse.  Ive checked the crank pins and they seem square.  I was wondering if they might be a problem with the flycrank?  But what it might be isnt clear to me.

saveric

[hallmodelspares]

If the flycrank is not in quarter with the wheels that might be the source. Is also that part all straight with no bends or slight wobble or play between the flycrank? If also you keep the flycrank connected oneside with the motion on the wheels all on the other side look and see if the flycrank is in line with the otherside

Edited May 24, 2020 by hallmodelspares
missed a bit

[Saveric74]

It seems inline.  I find it works fine in both directions if i loosen the nuts that tie the siderods on to the crank pins.  

[doilum]

13 minutes ago, Saveric74 said:

It seems inline.  I find it works fine in both directions if i loosen the nuts that tie the siderods on to the crank pins.  

Check that all holes on the coupling rods are truly circular and free to rotate on the bushes. Tiny imperfections cause binding.

[Saveric74]

Thanks for all the advice.  In the end it was the quartering as the wheel wasnt sitting flush to the axle.  Secondly the coupling rod had a very small distortion which is now corrected.  So all good now.  
 

Thanks,

saveric