Milnor 30015 Service Manual Download

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MSFD0701BE/9273BV

DESCRIPTION OF DUAL MOTOR DRIVE TRAIN

See the drive chart drawing (see Table of Contents) for part numbers and mechanical relationships among all
drive train components.

Cylinder Speeds

Machines covered by this section have four cylinder speeds. Slowest to fastest, these are wash, drain, low ex-
tract speed (E1), and high extract speed (E2).

Wash speed occurs during washing and rinsing bath steps. The cylinder reverses direction approximately twice
per minute as explained in “How the Machine Reverses” in this section.

Drain speed initiates water removal and distributes the goods evenly in the cylinder for efficient extraction.
Drain speed ranges from 69 to 81 RPMs, depending on the model.

Low extract speed ranges from 183 to 250 RPMs, depending on the model. Low extract speed occurs when an
extract precedes a wash, and before the machine accelerates to high extract speed.

High extract speed is used to extract the maximum possible moisture from the goods before the formula ends.
Range is 400 to 739 RPMs, depending on the model.

Drive Train Components and Operating Sequences

A microprocessor controller directs the machine through the required steps for each program. Controllers are

fully described elsewhere. Major drive train components include two motors (E1/wash and E2/drain), two clutches
(wash and extract), a jack shaft, and a system of V-belts and pulleys. To achieve various speeds, motors energize
and clutches actuate in the combinations shown in the following table:

Drive Train Component States

Action

E1/Wash

Motor

E2/Drain

Motor

Wash

Clutch

Extract

Clutch

Wash/Rinse

energized

not energized

engaged

not engaged

Drain

not energized

energized

engaged

not engaged

Low extract (E1)

energized

not energized

not engaged

engaged

High extract (E2)

not energized

energized

not energized

engaged

Slow down

(Coast time determined

by software or centrifu-

gal switch)

not energized

not engaged until

cylinder slows

sufficiently for a

safe return to wash

speed

engaged until

cylinder slows

sufficiently for a

safe return to wash

speed

Stop (Door open)

not energized

engaged

Drive Train Precautions

Do not subject the drive train to stress by instantaneous transitions from stop or wash to extract speeds,

nor from extract to wash speeds. To avoid damaging the mechanical components and hazardous conditions, the
motors and clutches gradually accelerate and decelerate the cylinder. These gradual speed changes are inherent in
all control systems and must not be bypassed through manual operation or programming modifications.

How Clutches Work

NEVER LUBRICATE CLUTCHES!

☞

Lubrication prevents clutches from transmitting sufficient torque.

Wash and extract clutches operate on 12VDC from a clutch circuit described in this section. The wash clutch

is engaged whenever the clutch relay K0 is energized (wash or drain). The extract clutch is engaged whenever the
relay K0 is not energized (low and high extract). Clutches have two major parts, a stationary coil (bolted to the motor
frame), and a rotating pulley assembly (bolted to motor shaft). Clutches are magnetically actuated and have metal
faces without friction material. Clutches are not serviceable.

The Clutch Circuit

The clutch circuit uses transformers and rectifiers to convert alternating current control circuit voltage to direct

current for clutches. Service voltage is first converted to control circuit voltage (240VAC for most models, 120
VAC for M4P, M5P, M6P, and M7P models). This voltage is fed to the clutch circuit transformer, where it is
converted to 16.5VAC, then delivered to the clutch rectifiers. There is one rectifier for each clutch, providing
12VDC. Fuses protect all components. Rectifiers and transformers are extremely reliable, and require no mainte-
nance. However, because rectifiers are sensitive to excessive voltage, in the unlikely event of burned fuses, check
for component damage before returning the machine to service. As a safety feature, the clutch circuit also prevents
cylinder rotation with the door open. Both clutches engage, locking the jackshaft when the door is open and power
is supplied to the machine.

Malfunctioning Clutches or Clutch Circuits

The low speed (wash speed) drive train is disengaged during extract. At the end of extract, the extractor is

designed to slow down before the low speed drive train engages. Although extremely unlikely in a properly
maintained machine, a malfunction could cause the low speed drive to engage prematurely (a possibility
common to all types of industrial machines which have both a high speed and low speed operating cycle).