Bush Hog 1812, Operator'S Manual

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OPERATION
1812 08/14 Operation Section 4-5
© 2012 Alamo Group Inc.
OPERA
T
ION
3. Tractor Horsepower
The horsepower required to operate the mower depends on several operating factors including the vegetation
to be cut, terrain condition, operator experience, condition of the mower and tractor, and others. For most
mowing conditions, the 1812 mower requires a tractor with a minimum of 50 HP. Operating the mower with a
tractor that does not have adequate power may damage the tractor engine. Exceeding 75 HP may cause
mower damage by overpowering the unit in heavy cutting conditions.
3.1 Drawbar
Constant Velocity and Standard Driveline .
Position the length of the drawbar from the end of the
tractor PTO shaft to the drawbar hitch hole according
to the operating speed of the mower. If the mower is
a 540 RPM unit, position the drawbar length from
shaft end to hitch hole at 14”. Do not use PTO
adapters. Use of PTO adapters will invalidate your
warranty.
3.2 Tractor Hydraulics
The mower center section and each wing are positioned with a hydraulic cylinder that are operated by the
tractor hydraulic pump. The tractor must have a minimum of 1 hydraulic control valve devoted to the mower.
If the optional hydraulic kit is used to raise and lower the wings independent of the center section, 2 hydraulic
remotes will be required.
3.3 Front End Weight
A minimum of 20% total tractor weight must be maintained on the tractor front end at all times. Front end
weight is critical to maintain steering control and to prevent the tractor from rearing up while driving. If the
front end is too light, add weight until a minimum of 20% total weight is reached on the front tires. Front
weights and weight carriers can be purchased through an authorized tractor dealership.
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3.4 Power Take Off (PTO)
Depending on the unit, the mower is designed to operate at a PTO speed of 540. Most tractors operate at
either 540, or a combination of 540 and 1000 RPM PTO speeds. The operating speed of the mower and
tractor can be determined by the number of splines on the driveline yoke and PTO output shaft. Those
operating at 540 RPM will have a 6-spline shaft and those operating at 1000 RPM will have a 20 or 21-spline
shaft.
Note:
Refer to the tractor owner’s manual for instructions to change PTO speeds on models that
operate at more than one speed.
If operating an older model tractor where the tractor’s transmission and PTO utilize one master clutch, an
over-running clutch must be used between the PTO output shaft and the driveline of the mower. An authorized
tractor dealer can provide the over-running clutch and its installation if needed.
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