Motor Under-powered or Something Else?

[SWTDriver]

I have just completed the High Level Kits chassis for the 2251 Collett Goods in EM gauge.

 

When I ran the chassis without the body or tender it ran very well. However once I got the body on and attached the tender it farted an spluttered for a bit and finally the gear wheel on the driving axle came adrift from the locktite that was holding it in place. I duly cleaned it up and used some more locktite to fit it back in place assuming I had used too little and the result was the a repeat performance.

 

My first thought is that the power to weight ratio is what might be causing the problem given that it ran OK as just the chassis, but I was assured by High Level that the motor is man enough for the job despite it being a smaller motor for the EM model compared with the on for P4.

 

My second thought is that the gear wheel on the driving axle is too loose in the first place as it was a very easy fit, making me think that I might have taken too much off the inside when I opened up the hole. Is there any way I could rectify this by making the hole big enough to fit an brass axle bearing and trying to make it a tighter fit.

 

Any suggestions would be welcome, thanks in advance.

[KalKat]

Are the wheels clear in the splashers?

 

 

Emma

[Gordon A]

A couple of pictures of the chassis and the underside of the body would be helpful.

 

Gordon A

[JeremyC]

I would agree with Kalkat, if the chassis runs well without the body and the problem only occurs with the body on then something in the body is fouling. If the motor can break the Loctite bond then it would appear to have plenty of power. I have used a number of HL gearboxes and found them an excellent item. If you don't trust Loctite to do the job of securing the gear [and to be honest without using industrial strength types I have doubts about the method long term) you could do what I have done on the two High Level gearboxes I have built which have used gears without locking screws and key the gear to the axle. 

Below are some photos of what I did.

 

Axle drilled 0.8mm to about half its diameter 

 

Key made from 0.8mm brass wire

 

Gear put on a mandrel and then drilled 0.8mm half in mandrel and half in gear. It's not essential to have lathe if you can find a piece of 1/8" brass, it was just easier.

 

Gear showing keyway

 

Axle fitted to chassis with gear on (Obviously the key has to be fitted after the axle is through the frame bush). The axle is still to be pushed into it final position. I do secure the gear with Loctite to prevent it moving sideways, but the drive is now taken through the key. 

Edited March 4, 2018 by JeremyC

[Guy Rixon]

Which "Loctite"? Most of the shaft retainers (6xx series) should be strong enough if properly cured. You might consider getting the specific kind for the size of gap: some of them can fill large gaps while maintaining concentricity, and some need a closer fit. Check the technical sheets. Also consider getting the oil-tolerant kind if the gear is exposed to lubricant.

[Jol Wilkinson]

Either something on the body is fouling the wheels/gears or bolting the chassis to the body is distorting the chassis and causing it to bind.

 

Try placing the body on the chassis (but not fixing it) and running it like that to see if that is the answer. I only ever tighten one mounting screw, leaving the other about one half turn loose with a drop of paint to lock it in place.