3-8.MARINE GEAR- MAINTENANCE INSTRUCTIONS.
The Model MG-514 Marine Gear is a marine reverse and reduction gear. The marine gear may
be operated continuously in either the forward or reverse position. Identical ratios in forward and reverse permit
the type of installation known as "twinning"; that is, mounting two gears on right-hand rotation engines and
running one gear in forward and the other gear in reverse to obtain opposite rotation of the propellers.
This marine gear is completely hydraulic in all phases-all bearings are oil lubricated, both clutches
are engaged by high pressure oil, and both clutches are cooled and lubricated by low pressure oil. Refer to
paragraph 3-8.1 for oil base maintenance instructions.
A mechanical lock-up, or come-home, feature is provided for clutch engagement in the event
emergency operations are necessary.
The forward clutch shaft and the r verse driving gear always rotate in engine direction. The
reverse clutch shaft and the reverse driven gear always rotate in anti-engine direction. When the forward
clutch is engaged, the output shaft gear will rotate in an anti-engine direction due to the gear meshing with the
forward pinion. When the reverse clutch is engaged, the output shaft gear will rotate in anti-engine direction
due to the gear meshing with the reverse pinion.
All pressures given in this section are under the following conditions only: An engine speed of
1800rpm with a recommended oil in the gear sump and a sump or heat exchanger inlet
temperature of 180 degrees F (82 C). Pressure readings taken under other conditions will
Description. The hydraulic system in the Model MG-514 Marine Gear distributes both high and
low pressure oil for clutch engagement, cooling, and lubrication functions. The sump, which is located in the
bottom of the main housing, contains an adequate amount of oil for all functions of the system. The oil pump
assembly pressurizes the oil for both high and low pressure requirements. The selector valve assembly is both
a pressure regulator and distributor for the hydraulic system: The manifold is not only a protective cover for the
clutches, but also a distribution component since it contains passageways for high and low pressure oil