Why Loco Engines Have Sandboxes near Wheels? A sandbox near wheels of loco engines improves braking system ensuring stoppage at a short distance without slipping from tracks. Most of us may not be aware of why loco engines have sandbox near wheels.
A sandbox is a container on most locomotives, multiple units and trams that holds sand, which is dropped on the rail in front of the driving wheels in wet and slippery conditions and on steep grades to improve traction. It improves braking system ensuring stoppage at a short distance without slipping from tracks.
There is a hopper (container) under the bogie of a train, close to wheels of locos. It contains fine sand. And its nozzle is open at the wheel-rail contact region. The sand may be delivered by gravity, by a steam-blast (steam locomotives) or by compressed air. So now we know what is a sandbox and why loco engines have sandboxes near wheels? Now let’s understand what the use of this box in a train is.
All of us have heard of a kind of hissing sound produced by a train when its brakes are applied. When brakes are applied to stop the train, sand from this box is sprayed on rails. Compressed air is used to spray sand grains on rails. During winter and rainy seasons or if any oily substances fall on rails, wheels tend to lose grips. In that case too, the loco pilot goes for sand spraying.
And it is operated manually. This means, it depends on loco pilots when to use the buttons meant for sandbox and how long to be used. If too much sand is applied, it can lead to problems, especially at the track points or level crossings, where the sand cannot slip sideways. Lastly, the sand increases the friction between rail and wheel flange, which counteracts the wheel flange lubrication; the reduced wheel flange lubrication increases the danger of the wheels climbing up the rail.
Content for this question contributed by Jemmima Abram, resident of Omaha, Douglas County, Nebraska, USA