Reel Drive System

1
Light Weight Fairway Mower
Reel Drive System
2
LWFM Slide Index
(Left Click Selection Box)
Reel Drive-Build the System
Backlap Valve-Off
Backlap Valve-Mow
Backlap Valve-Backlapping
Relief Valve Operation
Reel Drive Schematic
NEW LFM B Models
All Other LFM
3
REEL DRIVE SYSTEM THEORY OF OPERATION The Mow
valve is a solenoid actuated, pressure limiting
shuttle valve. It is used to control the flow to
the reel motors. The mow valve is energized
through the control module during mowing
operations. It limits pressure in the reel drive
circuit to 3000 PSI. The flow control valve,
located in the backlapping valve assembly, is a
manually operated flow restrictor. It is used to
control reel speed when backlapping. It is
adjusted by rotating the knob clockwise to
restrict and counterclockwise to increase
flow. The backlapping valve or directional valve
, located in the backlapping valve assembly, is a
hydraulically operated, three position,self
centering, closed center spool valve that changes
fluid flow direction. The knob, when pushed in,
directs the fluid flow to the motors for forward
cutting. When pulled out, the cutting units will
reverse direction for backlapping. The motors are
Danfoss.
4
Backlap Valve
(
Reel Pump
4

• Build the System

5
Mow OFF/ Neutral
In the neutral Position, oil simply flows through
valve assembly and back to tank. Notice oil is
free to travel out to the directional valve.
The center position of the directional valve is
closed and prevents oil traveling through the
motor circuit, so the oil takes the path of least
resistance and flows back to the reservoir (out
port T).
6
Backlap Valve

• Off

) (
)(
)(
6
7
When the mow solenoid valve is energized pressure
and flow are now routed to the flow control valve
and logic element. The flow control valve
determines the rpm of the reels. Pressure in the
reel circuit will vary according to the amount of
resistance that the cutting units are generating.
The logic element, compares pressure at the inlet
and outlet ports of the flow control valve. As
the flow is restricted, pressure builds on the
input side of the flow control valve to a value
higher than that on the output side. This forces
the logic element to open and dump excess flow to
the tank. As flow returns to the reservoir,
pressure to the input side of the flow control
valve drops and the logic element closes. The
logic element will continue this cycle as needed
to equalize pressure on both sides of the flow
control valve. After leaving the flow control
valve, fluid enters the top of forward/reverse
valve. The pressure oil shuttles the spool valve
down to allow hydraulic oil to the forward side
of the reel motors. When the mow valve is
de-energized pressure oil is then routed the
path of least resistance which is back to tank.
The flow control valve will then shuttle back to
the off position. Thus blocking the path for oil
to flow to the cutting units and stopping the
possibility of reel creep or wind milling. After
leaving the backlapping valve, flow is directed
to the forward side of the reel motors. The reel
motors are connected in series starting with the
left front, center motor, and right front.
8
Backlap Valve

• Mow

MowValve
)
)
(
)
PortB
PortP
VariableOrifice
(
(
(
(
PortA(Mow)
LogicElement
(
8
Port T
9
Reel Momentum OFF
The purpose of the reel momentum off is to allow
the reels to gradually slow down. If we abruptly
stopped our reels we would run the chance of
damaging the reel motors.(cavitation) When the
mow valve is de-energized the reels continue to
spin. While they continue to spin the motors
become pumps thus keeping pressure in the system
and holding the directional valve in the down
position. As the reels slow down, pressure
decreases and the springs on the directional
valve then center the spool to the OFF position.
This all happens in a matter of seconds.
10
Backlap Valve

• Off - Reel Momentum

MowValve
)
)
(
)
PortB
PortP
VariableOrifice
(
(
(
PortA(Mow)
LogicElement
(
(
10
Port T
11
Backlapping Valve The backlapping valve, located
in the backlapping valve assembly, is a three
position, self centering closed center spool
valve that changes fluid flow direction. The
knob, when pushed in, directs the fluid flow to
the motors for forward cutting. When pulled out,
the cutting units will reverse direction for
backlapping, and a switch is actuated to energize
the Mow Valves. Pushing the knob in stops the
cutting unit rotation Flow Control Valve The
flow control valve, located in the backlapping
valve assembly, is a manually operated flow
restrictor. It is used to control reel speed when
backlapping. It is adjusted by rotating the knob
clockwise to restrict and counterclockwise to
increase flow. The logic element, compares
pressure at the inlet and outlet ports of the
flow control valve. As the flow is restricted,
pressure builds on the input side of the flow
control valve to a value higher than that on the
output side. This forces the logic element to
open and dump excess flow to the tank. As flow
returns to the reservoir, pressure to the input
side of the flow control valve drops and the
logic element closes. The logic element will
continue this cycle as needed to equalize
pressure on both sides of the flow control valve.
12
Lets look at just the pressure sensing, flow
compensating, variable reel speed control,
Micro-Backlap valve for short. The pressure
sensing, flow compensating aspect of the Backlap
valve is accomplished with the logic element.
During backlapping the reel speed is turn down to
1 or 2 on the reel speed control knob. This
causes pressure/restriction, opening the logic
element, the excess oil is now dumped back to
tank through the logic element. When we apply
backlapping compound to the reels this causes
pressure/restriction on the other side of our
reel speed control. The logic element senses
this through the pilot line and compensates the
flow by closing the path to tank, thus sending
more oil to our cutting units, keeping a more
consistent reel speed. Giving us pressure
sensing, flow compensating
13
Backlap Valve

• Backlap

(
13
14
Backlap Valve

• Over Relief

MowValve
)
)
(
)
PortB
PortP
VariableOrifice
(
(
(
(
PortA(Mow)
LogicElement
(
14
Port T
15
LWFM Slide Index
(Left Click Selection Box)
Reel Drive-Build the System
Backlap Valve-Off
Backlap Valve-Mow
Backlap Valve-Backlapping
Relief Valve Operation
Reel Drive Schematic
Motor Case Drain Test
Return to Product Index
LFM B Models
All Other LFM
16
Reel Drive

• Build the System

17
Backlap Valve

• Off Position

Pilot Operated Shut-Off Valve
18
Backlap Valve

• Mow Position

Pilot Operated Shut-Off Valve
19
Backlap Valve

• Backlapping

20
Backlap Valve

• Over Relief

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Reel Drive
22
In section 8 of the technical manual, under reel
motor case drain test, is a procedure to allow
to test for reel motor internal leakage. The
procedure states to test all motors in the
circuit simultaneously by connecting a flow meter
in series on the return side after the last motor
in the circuit (the right side, as shown in the
slide above). Start the machine, operate at WOT
and restrict oil flow with the flow meter until
reaching 2500 PSI. Operate for 15 seconds.
Measure case drain, multiply quantity by four (to
get loss per MINUTE). THE LOSS SHOULD NOT EXCEED
1 GALLON PER MINUTE PER MOTOR. If exceeded,
rebuild or replace motor.
23
Reel Drive
FlowMeter

• Reel Motor Case Drain Test