This part is used in a machine which moves along the railway track vibrating the track so that the ballast underneath is compacted.

The round drum in the middle contains an eccentric weight which rotates, causing the vibration, and the cylinders sticking out of the sides are for lowering the rollers that transmit the vibration to the track. The smaller cylinders on top are a locking mechanism to ensure the rollers don't drop down when the machine is being moved around the railway at speed.