Edward Thomas excessive wheel slip

[Ian RParticipant @ianr]

5 Inch Edward Thomas

I have been running this loco for a few seasons and no issues with performance.

The last couple of times in steam I have found it very difficult to move the loco without incurring excess wheel slip even with very small use of regulator and drain cocks open. I have ensured the wheels have been degreased and tack

Any suggestions how why this has recently happened and what might be done to eliminate this issue I have ensured the saddle tank and side tanks are full of water to add weight over driving wheels.

 

[parovozParticipant @parovoz]

Has the suspension changed in terms of spring tension etc.  and or balance between drivers and trailing truck?

 

If not… just knurl the wheels 🙂

 

All the best…..

[Nigel Graham 2Participant @nigelgraham2]

Same track presumably?

Cleaned rails, so…

Driving-truck wheel bearings or brakes binding slightly?

I don’t know the specific regulator design but is it still capable of fine control or could it be lifting slightly off its seating surface when opened? That could give the effect of rapid, fuller opening which might be noticeable alternatively as a heavier exhaust beat than normal for the control settings. One way to test this might be to try moving off with the reverser notched back a bit.

 

[Ian RParticipant @ianr]

Would an issue with the springs cause the wheel slip

I have not checked if all four wheels are sitting squarely on the track

[duncan webster 1Participant @duncanwebster1]

If youve got all the weight on the front axle and the rear truck it wont be helping.

[duncan webster 1Participant @duncanwebster1]

If all the weight is on the front axle and rear truck it wont be helping

[Ian RParticipant @ianr]

I have today checked the suspension on Edward Thomas

The results are confusing the front leaf springs a very spongy and flex about half an inch

The rear springs are much stiffer and only flex about one eighty of an inch.

There seems to be no weight holding the front wheels down which seem to bounce on the track.

This I think is the cause of the wheel slip as front of loco has no traction.

How is this rectified new leaf springs on front or is there some adjustment to stiffen the suspension??

 

[Clive Brown 1Participant @clivebrown1]

A frequent problem with leaf springs is that they are too stiff, which is why tufnol is often used instead of spring steel. If your front springs are tufnol can you replace one or more leaves with steel? Half an inch sounds a lot of movement, both main axles should have approximately similar spring characteristics Most of the loco weight should be shared by the driving wheels with the very minimal load on the trailing pony truck.

[Ian RParticipant @ianr]

The front springs have a lot of movement and when you push down they are almost straight.

I think they need replacing ? or is there any adjustment there looks like a screw in top middle

Can you source replacement springs ?

[Clive Brown 1Participant @clivebrown1]

I doubt if suitable springs will be available “off-the shelf”. They are usually made to suit the particular model. The screw could perhaps be some form of adjustment, but might be a means of holding the leaf assembly together. Investigation is needed.

[Ian RParticipant @ianr]

I was wondering if an member of the forum has a set of drawings of the leaf springs on a 5 inch Edward Thomas that they would share with me.

Are these still available I have seen ones for 7 1/4 but not 5 inch

[noel shelleyParticipant @noelshelley55608]

From the original question – It seemed that the problem had suddenly occurred , springs weakening would not happen suddenly unless broken. From the ops reply the suspension does seem wrong. What about the load ? Is the riding trolley dragging or putting weight onto the loco. The drawbar pin is vertical and the jaw tight, not allowing vertical movement between the loco and trolley. What’s changed ? that may be the clue. Good luck. Noel.

[Ian RParticipant @ianr]

We have driven the loco without any driving trolley and it still has wheel slip the front two wheels seem to bounce on the track

I cannot see if the springs are broken and now looking to remove them and inspect.

[parovozParticipant @parovoz]

I would recommend ‘weighing’ the locomotive, there are various ways to do this and some of the regulars here may be able to point you to the right resources on methods. But basically, weighing means to measure the force being applied to the rails by each axle / wheel. So in general the spring load on all the driving axles should generally be the same. In full size terms, say 16 tons on each axle. The trailing truck should have less, as that is not contributing to tractive effort, so possibly 10 tons. One reason that locomotives have compensated suspension was to ensure that the axle loading stayed consistent over track undulation etc. So if springs are weak, then there is less load being taken on that axle. I have known people in our club to significantly improve performance by correcting spring tensions and balancing the loads on each axle.

 

All the best.

[Ian RParticipant @ianr]

Thank you for your reply

I have made a rough weight comparisons between the front axle and rear and I believe the front is half that of the rear.

I think the springs are weak and need correcting to balance the load.

I am having trouble finding how this is done on leaf springs where I find the information to adjust and correct this issue or make or acquire new leaf springs.

I may have located some drawings  no 6 but no indication of lengths etc of the springs

[duncan webster 1Participant @duncanwebster1]

Ian, I have scans of all the construction series from EiM. If you send me your email address via pm I’ll send them to you via dropbox

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