Cooper Instruments & Systems XST Tension Only Mechanical Force Gage - Manual (Page 3)

OPERATIONAL DATA
IMPORTANT!
When adjusting bezel-locking screw, #10, only tighten as much as is necessary to hold bezel in proper position.
DO NOT OVERTIGHTEN, as this will distort the thin housing of the dial indicator gauge; affect the smooth
action of the movement and produce false readings!
Your Force Gauge is ready to go to work for you without any special assembly. Upon removing it from the
storage case, it is only necessary to check the zero setting. This is done by placing the unit on a flat table with
the pressure button, # 4, at the top. Note that the dial bezel, # 3, is locked lightly by a knurled thumbscrew, # 10.
Simply loosen this knurled screw and then revolve the bezel in either direction, depending upon which way zero
may be off. Revolving the bezel causes the dial to follow. With zero positioned directly under the pointer tip,
again tighten the locking screw, and the instrument is ready to use.
Because of the sensitivity of the Cooper Gauge, zero should always be set with the unit resting on the lower or
thicker portion of the deflection beam as illustrated. This is the same position it occupies during calibration.
Ordinarily, zero will be retained indefinitely. However, under repeated stress or through accidental banging
around, it may go off slightly. Thus, it is a good plan to check zero occasionally.
Caution:
The small anvil, #6, against which the dial indicator plunger rides, should never be altered except by
factory technicians. This anvil has nothing to do with zero setting. By careful adjustment, it has been positioned
in such a way that, for full load application within the range of the instrument, the pointer will revolve 360°.
TAMPERING WITH THE SETTING OF THIS ANVIL AUTOMATICALLY VOIDS THE ACCURACY
GUARANTEE. If the anvil should be accidentally thrown out of position by dropping or striking against another
object, the entire gauge should be returned to the factory for resetting and calibration check.
HELPFUL POINTERS
It is a good plan to test the tightness of the hardened dial indicator plunger, #6, occasionally. This part is
screwed into a finely threaded seat and may sometimes work loose. This would cause the gauge to read high
and might be mistaken for an off zero condition. Be sure not to force the plunger tip too tightly when screwing it
down since, as explained, the threads are fairly delicate and might break off.
Note that threaded mounting holes have been provided in opposite faces of the “U” shaped deflection beam, #1.
In the upper mounting hole, a spherically recessed pressure button, #4, is screwed. This button is hardened
and plated. It receives the loading ball, #11. Force should be applied directly against this ball. In operation, the
deflection beam bends inward slightly, and the ball revolves, tending to keep the line of force vertical. A drop of
light oil on the ball assists this action.
Never fasten the “U” shaped deflection beam in such a way that the free movement of the upper portion will be
retarded. The lower or thicker “leg”, however, may be tightened as securely as desired, using a stud or bolt
through the threaded mounting hole.
Since the deflection beam is hardened, it is not possible nor would it be recommended, to drill and tap it once it
is in the field. If special mounting holes are desired, these can be provided during early stages of manufacture,
but must be specified at that time.
If a particular test calls for load application through a pulley, roller or chuck, etc., due care should be taken to
see that the load is applied in a true vertical line through the center of the top-mounting hole #4. Off-center
loading would introduce leverage, thereby increasing or decreasing readings from their true value. Universal
joints or hinged fittings should be carefully machined to obviate side slop or play. If in doubt about the best
method of applying load for specific arrangement, don’t hesitate to consult our Engineering Department.
Remember, a rough pencil sketch or snapshot will aid tremendously in understanding your problem. Never oil
the dial indicator at any point. It is unnecessary. If oil or other fluids should get on the unit, wipe off gently, but
well. Foreign matter lodging on the plunger, #6 will retard its free action, resulting in inaccurate readings.
If accidental overload is anticipated, a solid steel rod about 3/4 inch in diameter can be inserted at the center
point of the Gauge between the “U” shaped bar. Length of this rod should be figured so that the upper, flexible
half of beam will bottom against it, once the full capacity of the instrument has been reached. Further load will
CF 109 2 11/02