Technical information

Water tank
300R & 400R (and 500R from serial
number 0266)
Capacities:
300R/400R: 10 to 75 litres (2 to 16 galls)
500R: 10 to 110 litres (2 to 25 galls)
The tank is designed to automatically shut
off the flow of incoming water once the
desired measured quantity is achieved.
Mounted on the front of the tank body are
a graduated scale and carrier Passing
through the carrier is a pointer and pivot
pin. Once the pointer is set to the required
amount on the scale, the pointer and
scale carrier are locked together with a
wing nut and coach bolt.
Note: Always release and then re-tighten
the wing nut each time the pointer is
moved.
Both the scale carrier and pointer pivot pin
pass into the interior of the tank where the
scale carrier terminates in a cam. The
pointer pivot pin carries the float arm and
plastic float assembly and terminates at
the operating lever.
Moving the pointer along the graduated
scale effectively raises and lowers the
height of the float assembly in the tank.
Mounted on the outer L/H side of the tank,
adjacent to the scale carrier, is the water
inlet containing the water strainer.
Attached to the water inlet, on the inner
face of the tank, is the water inlet valve
assembly.
The water inlet valve (see illustration
below) consists of a body and cover
sandwiching a brass and rubber
diaphragm. The cover is machined to
carry the sprung pilot valve.
Water enters the valve body through the
strainer filling the chamber acting on the
rear rubber face of the diaphragm,
causing the diaphragm to stretch and lift
off the seat allowing water to enter the
tank.
There is a "pin hold' orifice in the centre of
the diaphragm allowing water to pass
through into a second chamber in the
valve cover where the pilot valve is
located.
The pilot valve is held off its seat, against
spring pressure, by trip lever allowing the
water to bypass the pilot valve and bleed
2.8 OPERATION