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OPERATION
RB60/72 02/11 Operation Section 4-5
© 2011 Alamo Group Inc.
OPERATION
2.3 Tractor Horsepower
The power required to operate a mower is determined by the tractor PTO horsepower. For most mowing
conditions, the RB60/RB72 mower requires a tractor with at least 20 HP for the RB60 and 25 HP for the RB72.
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.
2.4 3-Point Hitch
The tractor 3-point hitch must be rated to lift at least
522 lbs. for RB60 and 638 lbs. for RB72.
The RB60/RB72 mower is designed to be mounted
on a tractor with a CAT I 3-point hitch. Refer to the
tractor operator’s manual for the category of the
tractor being used. If the hitch does not conform to
ASABE CAT I dimensions, the mower may not fit or
raise properly. Consult an authorized dealer for
possible modification procedures to mount non-
conforming hitches.
Depending on the hitch category, certain size pins
are used to attach the mower to the tractor. CAT I
hitches require 7/8” lower and 3/4” upper diameter
hitch pins.
Standard Hitch
2.5 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. OPS-U- 0005
2.6 Power Take Off (PTO)
This 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 21-spline shaft. Note: The
mower will not operate on tractors equipped with a 1000 RPM 21-spline or 1000 RPM 20-spline, 1-3/4” shaft.
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. OPS-R- 0066