Horn Circuit - Kubota U20-3 Workshop Manual

U20-3, U25-3 WSM
f. Horn circuit
(1)Structure
(2)
(3)
(4)
The horn consists of acoustic diaphragm, point, horn coil and other parts. It comes in spiral, flat and
other types in construction.
Currently, the flat type is most widely used. A typical flat horn is shown at right.
(3)
(1)
(2)
(2)Function
Shown above is the horn drive circuit. When the horn switch is pressed, current flows to the horn relay
to get its contact P1 closed. The current from the battery now flows directly through the horn coil and
the contact P2, which magnetizes the core and attracts the moving plate. Then the contact P2 opens
itself and the current is interrupted. The magnetic force then disappears and the spring-loaded dia-
phragm comes back to the original position. The contact P2 closes itself, and the current flows again
through the coil to attract the moving plate. The above series of actions are repeated to keep the dia-
phragm vibrating, producing sound.
(1)
(6)
(7)
(5)
(8)
(9)
(5)
(7)
(4)
Electrical system (Mechanism section)
(1) Diaphragm
(2) Point
(3) Horn coil
(4) Nut
(1) Battery
(2) Horn switch
(3) Horn relay
(4) Diaphragm
(5) Core
(6) Coil
(6)
(7) Moving bolt
(8) Adjust nut
(9) Moving plate
V-M-10
(5)Stop screw
(6)Stay
(7)Air gap