ZF Marine ZF 285 Series Manual page 9

shorten the life of the clutches
Make sure the engine and propeller are at a standstill before carrying out any kind of operation
on the gearbox.
MECHANICAL TROLLING VALVE (M.T.V.)
The trolling valve is a device that allows the number of propeller revolutions to be changed indepen-
dently of the engine running speed. The M.T.V. is usually applied in the following circumstances:
1) when the boat speed is too high, even though the engine is idling.
2) when the rotation speed of the PTO must be greater than the propeller rotation speed.
The M.T.V. can be used in both drive directions and the maximum running speeds are:
- Maximum rotation speed = 800 rpm, for engines with maximum running speeds less than 2400 rpm.
- Maximum rotation speed = 1000 rpm for engines with maximum running speeds greater than 2400 rpm.
Use instructions
Check that the M.T.V. is deselected before engaging the gear. After engaging the gear, gradually move
the M.T.V. lever until the desired manoeuvre speed is reached.
When operating with trolling valve, the number of revolutions can be changed within the limits given
above.
It is forbidden to reverse the drive when the
M.T.V. is engaged.
ELECTRIC
(E.T.V.)
This is an electrical device that has the same functions and is used in the same way as the M.T.V.
The E.T.V. operates via a proportional solenoid valve.
TOWING
Towing can be done continuously for 8 hours. Check that the oil temperature does not go over 80°C.
The position of the control lever is of no importance when the engine is off.
Do not perform any operations on the transmission during towing, as the propeller may start
turning.
CONTROL VALVE SHIFT CONTROL LINKAGE
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TROLLING VALVE
9
15 = pressure-gauge
connection
15
Fig. 5.1
GB
CLUTCH
SLIP
CLUTCH
PRESSURE