Vollrath U421 Water Cooled - Manual (Page 27)

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SECTION 4
MAINTENANCE INSTRUCTIONS
4.1 FREEZER ADJUSTMENT
This section is intended to provide maintenance person-
nel with a general understanding of the freezer adjust-
ments. It is recommended that any adjustments in this
section be made by a qualified person.
4.2 PRODUCT TEMPERATURE ADJUSTMENT
A potentiometer is used to control the product tempera-
ture. To change the temperature of the product, follow the
steps below:
A. Loosen the two screws under the header display
sign, then pull sign out and down.
B. Use a screw driver to make desired adjustment. A
label near the potentiometer will give complete in-
structions. Figure 26.
Figure 26. Potentiometer
4.3 OVERRUN ADJUSTMENT
The product when served is a combination of air and mix.
Overrun is a measure of the amount of air blended into the
mix.
Overrun can be expressed in terms of the amount of
weight loss for a given volume. For example, if a pint of
liquid mix weighs 18 ounces (510 grams) and a pint of
frozen product with air added weighs 12 ounces (340
grams), the overrun is said to be 50 percent "18 oz. (510
grams) - 12 oz. (340 grams) = 6 oz. (170 grams)", (6 /12)
x 100 = 50%.
The overrun can be checked by placing a one pint
container on an ice cream scale and zeroing out the scale.
Then fill a one pint container with frozen product. The
container should be filled over the top and leveled with a
straightedge. The product should not contain any air
pockets. When weighed on an ice cream scale, one pint
(473 milliliters) of product should weigh 12 to 13 ounces
(340 to 368,5 grams).
The mix pump has been preset at the factory to produce
a product with approximately 40% overrun. Because of
differences in mix formulation, temperatures and baro-
metric pressure, this figure may vary. It will be necessary
for approximately 2 gallons (7,5 liters) of mix to be
pumped thru the freezer before changes in the product
are noticeable due to adjustments in overrun.
Overrun is controlled by the length of the air compressor
piston stroke within the piston cylinder. Lengthening the
stroke within the cylinder will increase overrun. Con-
versely, shortening the stroke will decrease overrun. To
perform an overrun adjustment, refer to the following
procedure:
A. Turn the mix pump switch to the OFF position .
B. Remove the lower back panel from freezer.
C. On air compressor side of pump, locate the long/
slender piston rocking arm. The rocking arm down-
ward travel is limited by a stationery cam. On the face
of the cam there is an overrun setting indicator plate
numbered 3 thru 8 and an adjustment knob. Figure
27.
D. The overrun setting is indicated by a pointed pin.
E. To adjust overrun, loosen the allenhead screw
(located within the center of the adjustment knob)
with the 5/32" (4mm) allen wrench provided. Rotate
the adjustment knob counterclockwise to a higher
number for higher overrun, or clockwise to a lower
number for lower overrun. Each number multiplied by
10 represents the overrun percentage (ie: #4 = 40%
overrun).
Overrun Adjustment
К К К К К
Figure 27. Overrun Adjustment