N&W Global Vending Koro Prime Espresso Installation, Operation & Maintenance Manual - page 28
© by N&W GLOBAL VENDING S.p.A.
20
01-2016 4875 00
OPERATION
The following paragraphs describe the operation of the
main components of the machine.
BREW UNIT CYCLE WITH FIXED CHAMBER
Whenever you power on the machine, the coffee unit will
make a complete rotation before performing the normal
cycle to make sure that the device will occupy the initial
position.
Whenever you require a selection based on coffee
beans
-For the models with no volumetric doser: the
grinder works so as to reach the coffee dose.
-For the models with volumetric doser: when the
doser is full, the ground dose is released into the coffee
unit.
Coffee falls into the brewing chamber arranged vertically.
The ratio-motor crank coupled on the disk outside the
unit rotates by 180°, thus causing the brewing chamber
to swing and the upper piston to lower.
1
2
3
4
5
6
Fig. 16
1- Upper piston
2- Brewing chamber
3- Lower piston
4- Pre-brewing spring
5- Swinging lever
6- External disk
Due to the water pressure, the pre-brewing spring sinks
and the lower piston goes down 4 mm, thus forming a
water cushion which allows an even use of the coffee
dose.
At the end of the dispensing cycle and during a 3-sec-
ond pause, the pre-brewing spring will discharge the wa-
ter layer through the third way of the dispensing solenoid
valve, lightly pressing the used coffee dose.
By completing its rotation, the ratio-motor makes the
swinging lever lift the pistons and the coffee dose.
While the brewing chamber is returning to its vertical
position, the scraper on the coffee funnel prevents the
used coffee dose from moving, dropping it.
The lower piston returns to the bottom dead centre.
Fig. 17
Fig. 18