The Transports are platforms, usually colored blue and red. They have a pair of wheels set on them that the player can move up and down by performing the Spin Dash on them, causing the wheels to rotate and moving the platform up and down like an elevator. Transports are set either against the wall or between the walls.
Sonic & Knuckles
The Transports made their first appearance in Sonic & Knuckles, where they are only seen in Lava Reef Zone Act 1. In this game, they are grey motors with a pair of metallic wheels on each side. These platforms can be found above or on the bottom of deep holes, while the wheels are set on roller chains between the walls. These platforms are the only way to reach the top or bottom of the deep holes.
When the player jumps on a Transport, he/she can face either the left or right direction. The player then has to perform the Spin Dash on the Transport, which will make the metallic wheels on the platform move, to make it move. Which direction the Transport moves depends on the direction the playable character is facing when starting to Spin Dash; facing the left direction will make the Transport move down, while facing the right direction makes the platform move up. The direction the Transport moves is a very decisive, usually depending on whether the player finds the Transport above the deep hole from the right direction or on the bottom of a hole from the left direction.
Sonic 3D Blast
In Sonic 3D Blast, Transports are blue colored platforms with wheels, which are only featured in Volcano Valley Zone. It is only used in the game to reach to the top of some taller rock tabs. When the player jumps on the Transport, the player has to perform the Spin Dash normally on it to make it move up. However, if the player stops using Spin Dash, the Transport starts falling down to the ground. If the player slips below the falling Transport, the playable character will be crushed, causing him/her to lose a life.
Transports in Sonic Blast are loosely similar to ones in Sonic 3D Blast, except that they are smaller and have red wheels on the platform. They are only featured in Red Volcano Zone Act 2, where they are set against the wall. The player has to use them to reach the top of the walls or slowly descend into the bottom of holes. While Sonic has to use them, Knuckles can ignore them and climb along the walls.