Dog clutch

The two parts of the clutch are designed such that one will push the other, causing both to rotate at the same speed and will never slip.

[1] Dog clutches are used inside constant-mesh manual transmissions to lock different gears to the rotating input and output shafts.

[2] Racecar, motorcycle, and large truck transmissions, having higher performance demands and less need for smooth engagement than passenger cars, commonly employ dog clutches alone (without the use of synchronizers) to engage gears due to their high strength and durability and low complexity and weight.

[4] Oftentimes boats with inboard engines, such as sailboats, will use a dog clutch to engage the drive shaft to the transmission.

Shifting from neutral to forward or reverse often results in a large "clunk" noise that can be heard by occupants as the clutch engages suddenly.