Circuits; Battery - Husqvarna PT26D Workshop Manual

Circuits

The circuits for the electric system for PT26 are designed in a differently than for older machine types. On
older machines it was possible to trace the path of the electric power along a line from the battery over the
fuse, switch and relay connections to the consumer load.
The principle behind the electric system for PT26 is that the circuit board is feed from the battery via the
main fuse FU13 on the battery pole fuses FU3 and FU12 behind the battery.
The circuit board voltage measurement is shown on "Circuit diagram 3" on page 147.
The circuit board is the machine's "electro-centre", where all switches, sensors, etc. are hooked up and
provide incoming electric impulses or commands. See "Placement of circuit card connections, melt fuses
and LEDs" on page 157 and "Connectors on the circuit card" on page 158.
The circuit board's logic is built up with "digital relays and switches", which under consideration of any inter-
lockings sends an output signal to the respective consumer loads.
The circuit board is equipped with automatic fuses as well as melt fuses, see "Fuses" on page 39.
As an example of a circuit solution, the circuit
for the power take-off solenoid clutch is
described.
The power take-off shaft (and thus the cutting
unit) is engaged with the switch for driving the
cutting unit,PTO switch. See "Circuit
diagram 8" on page 152.
If no interlockings are active, the circuit board
transmits an output signal (supplies power) to
the solenoid clutch. PTO clutch, see "Circuit
diagram 4" on page 148.
A number of input signals are required to
determine whether interlocking of the power
take-off is necessary.
If the safety circuit is activated, see "Safety
System" on page 40, the PTO-switch is
pressed, a high gear selected, the cutting unit
lifted to its top position or the fuse FU1
tripped, the circuit board does not release
voltage to the solenoid clutch.

Battery

The machine is equipped with a sealed
"maintenance-free" battery. The battery has an
inspection hole that displays different colours:
• Green = OK.
• White = Charge the battery.
• Red = Replace the battery.
The battery poles is equipped with adapter
ferrules of lead for standard cable lugs. It is
important that good contact is made between
the adapter ferrule and battery poles.
DESIGN AND FUNCTION
1. Drive pedal sensor
2. Sensor p-brake
3. Switch driver's seat
4. Switch low gears
5. Switch PTO
6. Sensor max speed cutting unit
Solenoid clutch circuit
Battery
7. Solenoid clutch
8043-194
8009-796
37
English-