The Dry Sump; The Power Clutch - APRILIA RSV Mille 1000 1999 Technical Training Course

Aprilia Consumer Service Spa
Technical Service and Training
Release 4 july 99

The dry sump

A further innovation brought by Aprilia in producing this new engine is the use of dry-sump
lubrication, which allows a more rigid and compact engine block that the "wet-sump" solution. The
system makes use of a second trochoid pump for recovery and an external oil tank, as well as a
radiator positioned in front of the engine.

The power clutch

The RSV Mille has a clutch with hydraulic control,
assisted by the esclusive PPC patent (Pneumatic
Power Clutch) to check bouncing of the rear wheel.
When decelerating suddenly, the weight of the
motorcycle is transferred instantly to the front,
lightening the rear axle. In high-powered two-
cylinder engines this phenomenon is accentuated by
the high "engine braking" effect; this can cause the
so-called bouncing, or the tendency of the rear
wheel to block and lift off the ground, endangering
the stability of the bike and, consequently, the
vehicle's performance and safety.
Aprilia has found the ideal solution to this problem
exploiting the variations in pressure which occur in
the intake ducts when the throttle is opened and
closed, to lighten the load on the clutch springs. By
connecting the intake ducts to a "lung" situated at the
side of the clutch group, the vacuum created when
the throttle is closed decreases the load exerted on
the disks by the springs, while when the throttle is
opened again the clutch resumes operation under
normal weight conditions, thus transferring all the
power to the rear wheel.
This system also allows reduction of the force
applied on the lever on the handlebar, when the bike
is running at low rev speeds.
This material is didactic and
may be changed following the technical
development of the product