Bogie Control

[Tim Hale]

The DJH S15 on the workbench is causing a real headache- the front wheels tend to climb the crossing Vee and derail.

I have checked (and re-checked) the usual suspects- back to back, the crossing dimensions- all OK. I have also added lead above the front axle of the bogie and a certain about of downforce on the bogie- but still it climbs.

Not every turnout, only one right hand which is the shortest on the layout.

I am running out of options and I I have no idea how to fix the problem.

Tim

[Will L]

Tim

To have a fair chance of spotting the problem we would need to know a lot more about the way the loco chassis works; what sort of suspension,if any, your using; how the bogie is attached to the loco; and what constraints that lot puts on the way the bogie moves and weight is distributed.

But first I'd just check the bogie runs OK by it self, away from the loco, just in case it is a wheel that doesn't run true one way or another. Then I would check if either bogie wheels or frame are catching on the loco body/frames somewhere and are being prevented from moving far enough sideways. You did say it was happening on your sharpest point.

Will

[Tim Hale]

Will,

The bogie works perfectly within the longer turnouts but it cannot avoid climbing into the Vee when attempting to negotiate the fiddleyard turnout.

The bogie works perfectly detached from the loco but I begin to suspect fouling is the culprit.

Tim

[Philip Hall]

Tim,

I'd place the chassis on a mirror (this helps you see what's happening underneath) or a sheet of glass, surface table, anything dead flat and smooth will do. Slide the bogie from side to side in the manner in which it would move as it enters a turnout. If it slides smoothly raise it slightly with a sheet of Plastikard and try again. When (if) you find a point where it catches, look all around, perhaps checking the clearance in the frames for the wheels. Check also that the bogie cannot move too much fore and aft on the pivot, again causing fouling on the frames.

If the bogie is pivoted in the centre, another problem might be that the underneath of the frame spacer or the top of the bogie is not perfectly smooth, causing it to catch as it slides.

Philip

[Tim V]

Can you swap the wheels side to side? I found on one truck that the flange was just slightly below the recommended amount. I've now replaced that wheelset.

[jim s-w]

Hi Tim

Does a mint block go through the turnout? Have you looked at what the other axle is doing when the lead axle derails? Sometimes it can be the other end of the vehicle that's causing the problems.

Can you remove the bogie and does it run through ok on it's own?

Hth

Jim

[Tim Hale]

The bogie is OK when detached therefore it might be a fouling issue.

I need to get this right as the next build is a PDK H15 with even less room for movement.

Tim