Basically the title. Considering that train wheels are made of metals and run on metal tracks, how do they prevent wheelslip or loss of traction especially when starting with heavy loads or when going uphill? I’ve heard of sandboxes which can be used to provide more grip by spraying sand onto the track but I’m not sure if they’re still prevalent.
Thanks!
In: 72
You’re correct that the friction between the wheel and the rail is much less than that of a rubber tire on a road. Because of that, the acceleration of trains is usually much slower than that of a passenger car. Many modern passenger trains are what’s called electric multiple units, where many of the axles along the train are powered. This gives the train a higher portion of the total mass that rests on powered axles, usually allowing them to accelerate faster than locomotive-hauled trains.
Sometimes the wheels do slip and sand is still used to mitigate this during certain less favorible conditions. When the wheels slip during braking it can cause flat spots on the wheels which you can hear as a train passes. These have to be removed by machining a layer of metal from the wheels.
Leaves are particularly bad for traction on railways, so much so that some passenger railways even adjust their timetables to add extra time during the fall to account for the slower acceleration and braking.
Latest Answers