Power shifting transmissions, e.g. automatic transmissions, are traditional
ly shifted from gear A to B by disengaging a clutch belonging to gear A and
engaging a clutch belonging to gear B. This paper tries out the idea of em
ploying a third clutch. In practice, such a third clutch can be one of the
clutches which is traditionally used only for other gears. This means that
the new concept can be used with only a control software update in an ordin
ary gearbox. The trade-off between comfort and wear. which is experienced i
n the traditional control concept, becomes less troublesome. The wear, or t
he discomfort, can be reduced to roughly half of that corresponding to a tr
aditionally controlled upshift. The work finds the largest potential in usi
ng an extra clutch which belongs to a gear higher than the high gear in an
upshift. The theoretical study is carried out with a general and simple mod
el. but a simulation example is added using a more detailed model of an exi
sting gearbox.