FORM 160.73-O2 (605)
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YORK INTERNATIONAL
GENERAL
The YORK Model YK MaxE
TM
Centrifugal Liquid
Chill er is completely factory-packaged including evapo-
rator, condenser, compressor, motor, lubrication system,
OptiView Control Center, and all in ter con nect ing unit
piping and wiring.
COMPRESSOR
The compressor is a single-stage centrifugal type pow-
ered by an open-drive electric motor.
The rotor assembly consists of a heat-treated alloy steel
drive shaft and impeller shaft with a cast alu mi num,
ful ly shrouded impeller. The impeller is designed for bal-
anced thrust and is dynamically balanced and over-speed
tested. The inserted type journal and thrust bear ings are
fab ri cat ed of aluminum alloy. Single helical gears with
crowned teeth are designed so that more than one tooth
is in contact at all times. Gears are integrally as sem bled
in the compressor rotor support and are fi lm lu bri cat ed.
Each gear is individually mounted in its own journal
and thrust bearings.
The open-drive compressor shaft seal is a double bellows
cartridge style with ceramic internal and atmospheric
seal faces. The seal is oil-fl ooded at all times and is
pressure-lubricated during operation.
CAPACITY CONTROL
Prerotation vanes (PRV) modulate chiller capac-
ity from 100% to as low as 15% of design for
normal air con di tion ing applications. Operation
is by an external, elec tric PRV actuator which
automatically controls the vane position to main-
tain a constant leaving chilled liquid tem per a ture.
COMPRESSOR LUBRICATION SYSTEM
(See Fig. 8)
The chiller lubrication system consists of the oil pump,
oil fi l ter, oil cooler and all interconnecting oil piping
and pas sag es. There are main points within the motor-
com pres sor which must be supplied with forced lu bri -
ca tion as follows:
1. Compressor Drive Shaft (Low Speed)
a.
Shaft
seal.
b. Front and rear journal bear ings – one on each
side of driving gear.
c. Low speed thrust bearing (for ward and re verse).
2. Compressor Driven Shaft (High Speed)
a. Forward and reverse high speed thrust
bearing.
b. Two journal bearings.
3. Speed Increasing Gears
a. Meshing surfaces of drive and pinion gear teeth.
To provide the required amount of oil under the nec-
es sary pressure to properly lubricate these parts, a mo tor
driven submersible oil pump is located in a remote oil
sump.
Upon pressing of the
COMPRESSOR START
switch
on the Control Center, the oil pump is immediately
en er gized. After a 50 second pre-lube period, the com-
pres sor mo tor will start. The oil pump will continue to
run dur ing the entire op er a tion of the compressor, and
for 150 sec onds dur ing compressor coastdown.
The submerged oil pump takes suction from the sur-
round ing oil and discharges it to the oil cooler where heat
is rejected. The oil fl ows from the oil cooler to the oil
fi lter. The oil leaves the fi lter and fl ows to the emer gen cy
oil reservoir where it is distributed to the com pres sor
bearings. The oil lubricates the compressor ro tat ing
components and is returned to the oil sump.
There is an emergency oil reservoir located at the
high est point in the lubrication system internally in
the com pres sor. It pro vides an oil sup ply to the var i ous
bear ings and gears in the event of a sys tem shut down
due to power fail ure. The res er voir, lo cat ed on the top of
the com pres sor, allows the oil to be dis trib ut ed through
the pas sag es by grav i ty fl ow, thus pro vid ing necessary
lu bri ca tion during the com pres sor coastdown.
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