Weight of a four wheel locomotive

[Henri]

Today I did some test runs with my scratch build M66 four axle tram locomotive. Of course the body weights nothing yet, but I was surprised to find the Otto drive didn’t have much traction. Actually, it didn’t move at all!

Putting the weight out of the boiler of the Otto onto the chassis did increase grip tremendously. Now I’m wondering what does an average four axle LGB engine weight? What total weight should I aim for? Now is the time to add additional weight as much as necessary. It should be able to pull three coaches with four wheels each (bogies).

 

[PhilP]

Without going upstairs, and getting a loco...

If you can get your loco to weigh about the same a s the weight from the donor Otto, that will be a good starting point.


If I strip the weight(s) out of a loco (to make space for batteries etc.) I weigh the removed weight, and try to put the same amount of weight (total) back into the loco. - This is batteries + some weight, normally.

PhilP.

 

[MTheStrong]

Many years ago I conducted trials with Stainz locos to find the optimum weight. This turned out to be 2.2Kg and coupled with the removal of the traction tyre improved the haulage capacity and electrical contact of the loco. For the Otto type I found that 1.75Kg was the optimum weight, again removal of the traction tyre improves the electrical contact. I used fishing lead pellets for the weight and contained them in small plastic bags.

AustriaNG I believe will confirm the weight for the Stainz

Martin

 

[David1226]

It sounds as if that, without some weight, we might have a long wait for the train

David

 

[JimmyB]

Many years ago I conducted trials with Stainz locos to find the optimum weight. This turned out to be 2.2Kg and coupled with the removal of the traction tyre improved the haulage capacity and electrical contact of the loco. For the Otto type I found that 1.5Kg was the optimum weight, again removal of the traction tyre improves the electrical contact. I used fishing lead pellets for the weight and contained them in small plastic bags.

AustriaNG I believe will confirm the weight for the Stainz

Martin

No traction tyres on an Otto, or at least mine and others I have seen.

 

[Greg Elmassian]

yes, would expect that zero kg would result in zero traction

That motor block is not equalized at all either is it?

Greg

 

[LGB-Sid]

My stainz weights around 1600 to 1850 gramms they got lighter in later life it seems, The conversions I have done using stainz motor blocks I have got back up to around 1600 gramms.

 

[AustrianNG]

I have upgraded most of my Stainz from the old standard weight of 1.8 kilos (Before lead was banned) to around 2.2 kilos as Martin above says.
I too have taken most of the traction tyres off with no difference in traction.
The newer Stainz with the lighter alloy weights inside suffer in tractive terms, so I add as much weight as possible.

Several other of my newer LGB locos are somewhat lacking in tractive power - I shall have to buy another roll of code 4 lead and load them up.

 

[Paul M]

It sounds as if that, without some weight, we might have a long wait for the train

David

You didn't fall for that old trick surely?
Seriously, I would have thought putting TOO much weight on to you locos may burn out the motor

 

[MTheStrong]

You didn't fall for that old trick surely?
Seriously, I would have thought putting TOO much weight on to you locos may burn out the motor

You are right about too much weight. The point that I and Paul (AustrianNG) were making was that we found the optimum weight for the Stainz through trial and error. My upgraded Stainz and other similar locos, Trams, Spremberger and Kleine Dicke, have continued to run without having to replace the motor.

Martin

 

[Paul2727]

Hope this helps.
Standard locos with weights in situ:
20212 Stainz (No: 2) 1.859 Kg. B gearbox.
Otto (No: 1) 1.662 Kg.
2040C Stainz (No: 4) 1.587 Kg. C Gearbox. (Clam-shell.)
Regards,
Paul.

 

[a98087]

With adding weight, I’ve always been told to make sure that the wheels can still slip if the loco were to stall By hitting an obstacle

and tyre wheel weights, or old foreign coins make good testing weights.

I like to cast my own weights, but that’s a different conversation

Dan

 

[Paul2727]

Look on the bright side, at least there should be enough room in a tram loco body to add enough weight.
That is why my rail truck project is now in it's second incarnation.
Try getting enough weight into an open backed rail truck... Looks like I'm going to have cram about 3/4 of this block into her to get her to pull anything. I see a large crate 'load' on the horizon. Yes there is the bare bones of an Otto at her heart.
See below:
Paul.

 

[Henri]

Ok, this is good info.

Now the next food for thought. If an Otto, which drivegear I’m using, has an optimum weigth of 1,6 kg, what would be an optimum weight if I add two more axles, as in a boogie? The 1,6 kg will then be carried by four axles, not by two...

So how much should I increase the weight so the drivegear has 1,6 kg of ‘load’..?
(Maybe trial & error with a scale to find out... hmmm)

 

[FatherMcD]

I have upgraded most of my Stainz from the old standard weight of 1.8 kilos (Before lead was banned) to around 2.2 kilos as Martin above says.
I too have taken most of the traction tyres off with no difference in traction.
The newer Stainz with the lighter alloy weights inside suffer in tractive terms, so I add as much weight as possible.

Several other of my newer LGB locos are somewhat lacking in tractive power - I shall have to buy another roll of code 4 lead and load them up.

When you say that you have taken the traction tyres off, how exactly have you done that? Did you replace the wheels, fill the groove with metal, plastic or whatever?

 

[JimmyB]

Ok, this is good info.

Now the next food for thought. If an Otto, which drivegear I’m using, has an optimum weigth of 1,6 kg, what would be an optimum weight if I add two more axles, as in a boogie? The 1,6 kg will then be carried by four axles, not by two...

So how much should I increase the weight so the drivegear has 1,6 kg of ‘load’..?
(Maybe trial & error with a scale to find out... hmmm)

IMHO, if you add more axles but the drive axles remain at two, then the optimum weight remains the same. Only if you increase the number of drive axels can you increase the weight.

 

[Paul2727]

Ok, this is good info.

Now the next food for thought. If an Otto, which drivegear I’m using, has an optimum weigth of 1,6 kg, what would be an optimum weight if I add two more axles, as in a boogie? The 1,6 kg will then be carried by four axles, not by two...

So how much should I increase the weight so the drivegear has 1,6 kg of ‘load’..?
(Maybe trial & error with a scale to find out... hmmm)

That would depend a lot on whether the bogie was floating or weight bearing.

 

[Henri]

That would depend a lot on whether the bogie was floating or weight bearing.

Weight bearing.

 

[musket the dog]

If you're looking to get scientific, there is a handy-dandy equation ready made for the situation.

What you're looking for is R=(Fa)/L Where:

R is the force at the motor bogie pivot
F is the force of the mass you will add
a is the distance from the motor bogie pivot to the centre of the mass
L is the distance between the two pivots

In your case we are looking to get 1.6Kg (15.7N) at the motor bogie pivot so we can rearrange the equation to be F=(Ra)/L, you would just need to pick the point where you can best fit the mass into the body (a). F will be the force of the mass you need to add.

Please feel free to correct me, anyone who is more comfortable with physics first thing in the morning!

Probably better explained by Engineer's Toolbox, about half way down the page, under Beam Supported at Both Ends - Eccentric Load

Just remember to convert the mass to Newtons, and work in meters. Apolagies if I'm over simplifiing what you might already know!

The other thing to consider would be the drag on the wheels in the other bogie, mass added to the loco generally will make this more substantial and undo the good work the mass does to aid traction.

Edit: Just to say as well, the simple answer you might be looking for is that if you add it dead centre between the pivots, you would want 3.2Kg to have 1.6Kg acting on the motorblock

 

[dunnyrail]

Ok, this is good info.

Now the next food for thought. If an Otto, which drivegear I’m using, has an optimum weigth of 1,6 kg, what would be an optimum weight if I add two more axles, as in a boogie? The 1,6 kg will then be carried by four axles, not by two...

So how much should I increase the weight so the drivegear has 1,6 kg of ‘load’..?
(Maybe trial & error with a scale to find out... hmmm)

Interesting concept but normally In our scale the pony wheels are just flopping about to look pretty, some have a springing arrangement that will help to spread the weight a little but this is an awfully complex matter that real Railways have to grapple with using precise instrumentation to measure the load on each wheel. I somehow doubt that Much of the weight from the original motor block may be put on any pony truck, if it were the haulage capability would be severely reduced.

However in times gone by I had a Roundhouse 0-6-2 and the haulage capability of the locomotive we severely reduced by that truck, a Tender and an additional set of drivers when compared to another Roundhouse Loco that was an 0-4-0 without a tender.