Vollrath 219-02 User Manual

Page 21

SECTION 4

MAINTENANCE INSTRUCTIONS

4.1

OVER-RUN ADJUSTMENT

The product when served is a combination of air and

mix. Over-run is a measure of the amount of air blended

into the mix.

Over-run 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 and a pint of frozen product

with air added weighs 12 ounces, the over-run is said to

be 50 percent (18oz. – 12oz.= 6oz., (6÷ 12) x 100=

50%).

The over-run 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 of product should weigh 12 to 13 ounces.

The mix pump has been preset at the factory to produce

a product with approximately 40 percent over-run.

Because of differences in mix formulation, temperatures,

and barometric pressure, this figure may vary. A product

with the proper amount of over-run is firm and dispenses

at a smooth even rate. A product in which the over-run

is too low, is yellow, heavy, icy, hard or stiff, and

dispenses at a slow or pulsating rate. A product which

has small air pockets and dispenses smoothly, but with

an occasional popping as the product leaves the spigot,

has the over-run set too high. It will be necessary for

approximately two gallons of mix to be pumped thru the

freezer before changes in the product are noticeable

due to adjustments in over-run.

Over-run is controlled by the relative position of the

piston stroke within the pump cylinder. Raising the

stroke within the cylinder will increase over-run.

Conversely, lowering the stroke will decrease over-run.

To adjust the mix pump for a higher over-run, refer to

Figure 14, and follow the adjustment procedures below:

CAUTION

THE MIX PUMP SWITCH MUST BE IN THE OFF

POSITION WHEN SERVICING OR CLEANING

PUMP.

A. Remove two knobs and safety guard covering drive

mechanism.

B. The position of the stroke is adjusted by loosening

the jam nut (B) above the drive clevis (C) and then

turning the drive clevis up for a higher over-run.

CAUTION

THE DRIVE MECHANISM MUST BE

POSITIONED AT THE TOP OF THE STROKE.

THE TOP OF THE STROKE IS WHEN THE CAM

ROLLER IS IN ITS HIGHEST POSITION. PUMP

DAMAGE WOULD RESULT IF PISTON WERE

TO CONTACT CYLINDER TOP BEFORE

REACHING TOP OF STROKE. A 180 DEGREE

TURN OF THE CLEVIS IS APPROXIMATELY

AN OVER-RUN OF 2-1/2%.

Figure 14. Over-Run Adjustment

GUIDE RODS

PISTON

CYLINDER TOP

DRIVE PIN

CAM ROLLER