Boat reduction gearbox with clutch
MCD Twin Disc

The Marine Control Drive or MCD is a variable speed drive available in a range of sizes with power capacity from 160 to 4500 kW (215 to 6035 HP) at 1800 RPM. The MCD has proven its worth, particularly in tug applications but also in ice breakers, dredgers and fire fighting vessels. The system provides distinct operational advantages for any vessel requiring accurate positioning or a high degree of slow speed maneuverability while the main engine powers another action. There are three sizes with five models for each size to cover the range up to 4500 kW.

The very latest developments include changes to the clutch on the very largest model enabling it to transmit 3000 kW with full modulation without any restriction. The basic torque transmission components of the MCD are similar to those of the multi-disc clutch. A stack of friction discs compressed to a greater or lesser degree is mounted alternately on the driving and driven shafts. An oil film flows continuously between these discs. Consequently, the torque is transmitted through a hydroviscous media and without wear as the discs are not in contact during the slipping phase. When lock-up is achieved, the input and output speeds are synchronized; thus efficiency is maximum (99%). This advantage is important versus other couplings where output shaft slip, relative to the input shaft, is required to transmit the torque.