Going back to college physics, we were all a bit surprised to learn that the area of contact was not a factor in the equation for friction. Friction is calculated simply Frictional force = force normal to the plane x coefficient of friction.
Axle loading is a real good reason to have more axles though. Light rail/iffy roadbed? More wheels means less load on the rail under each wheel.
0-6-0 diesel yard switcher
Moderator: Harold_V
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Re: 0-6-0 diesel yard switcher
there is one factor for having more wheels on the track... if you have a small slick spot on the rail, an 0-4-0 will lose up to 1/4 of its traction when a wheel hits that spot. A 6 wheel locomotive will lose about 17% in the same scenario, assuming equal weight distribution. because track conditions are so varying, locomotives with more "feet on the ground" tend to be able to dig in a little bit better.
There is a practical limit on the amount of load that the wheels and rails can take without damage. lots of bridges used to have weight limits that meant bigger locomotives weren't allowed to run. ditto for light rails and such. that's one reason why the Russian decapods were popular with small branch line roads.
There is a practical limit on the amount of load that the wheels and rails can take without damage. lots of bridges used to have weight limits that meant bigger locomotives weren't allowed to run. ditto for light rails and such. that's one reason why the Russian decapods were popular with small branch line roads.
Re: 0-6-0 diesel yard switcher
Not sure if it is the same on steel-tired locomotives as it is on cars, but adding weight to a car wheel increases traction, but at a decreasing rate.
Steve
Steve
Re: 0-6-0 diesel yard switcher
We have a 10 wheeled semi tractor we converted to a motorhome, until we built some weight on top of it it was dangerous to drive at highway speeds, it could swap ends easily. Some people "single" their conversions by removing one of the rear axels to get more weight on the rubber and improve traction. Weight -vs- contact area is a balance.