The four carriages of the Hamburger Hochbahn accelerate smoothly and powerfully. The passengers feel the speed but are hardly disturbed at all by annoying travel noise. The new metro trains are pleasantly quiet. Comfort is further increased by the effective suspension system.

The light vehicles accelerate briskly, without jolting and require little energy.

• The vehicles must accelerate without jolting

• Lightweight gearboxes are used to keep total mass low

• The gearbox must be as quiet as possible irrespective of the temperature

A quiet gearbox depends on gears and shafts with little clearance

• There must be no change in clearance due to the difference in thermal expansion between aluminium (the housing) and steel