Reach adjustable steering column assembly

A steering column assembly for a vehicle, comprising:

• a telescopic shroud comprising an upper shroud part and a lower shroud part, the upper part being adjustable to slide over or slide into a lower part to provide adjustment for reach of the steering column assembly,
• a steering shaft which is supported by the telescopic shroud, and
• a clamp mechanism which releasably fixes the upper shroud part and lower shroud parts in position relative to one another in a locked condition whilst permitting relative axial movement of the first shroud part and second shroud part when in an unlocked condition, in which the clamp mechanism comprises:
• a first cam arranged to pivot around a first pivot axis that is fixed relative to the upper shroud part and carrying a set of teeth formed on a part of a periphery of the first cam,
• a second cam arranged to pivot around a second pivot axis that is fixed relative to the upper shroud part and carrying a set of teeth formed on a part of the cam periphery,
• the two pivot axes being spaced apart in an axial direction of the shroud;
• a cam follower that is fixed relative to the two pivot axes and relative to the upper shroud portion that carries a first rack of teeth that face the teeth of the first cam and a second rack of teeth that face the teeth of the second cam, the first rack being offset axially from the second rack in the axial direction of the upper shroud portion;
• and a locking mechanism that is operable to rotate the two cams around their pivot axes between a first position in which the teeth of both cams are held clear of the respective facing rack of teeth of the cam follower and a second position in which the teeth of both cams are urged into engagement with the teeth of the respective rack of the cam follower,
• whereby axial movement of the cam follower as the shroud collapses whilst the clamp mechanism is in the locked position causes the first cam to rotate in a direction that causes an increasing force to be applied from the teeth of the first cam onto the teeth of the first rack of the cam follower
• and whereby axial movement of the cam follower as the shroud extends whilst the clamp mechanism is in the locked position causes the second cam to rotate in a direction that cause an increasing force to be applied from the teeth of the second cam onto the teeth of the second rack of the cam follower whilst the second cam moves in an anticlockwise direction to reduce the pressure on the cam follower.