10
2.4 DC THEORY OF OPERATION
IBP BOARD
The IBP board is an integrated board that contain the Main Procesor section and the Power supply section.
The operating voltage for the Main Processor is 5VDC and they are generated and supplied by the Power Supply
section.
These 5VDC are then supplied to the Optoencoder. The Main processor section transforms 5VDC in 3.3VDC to supply
the distance and diameter potentiometers.
INCREMENTAL ENCODER BOARD MAIN SHAFT
The optoencoder receives 5VDC from the IBP box. This voltage can be measured on the IBP box at X3, pin 6. Output
directly goes to the IBP box. The optoencoder is built so there are no adjustments.The encoder disk consists of a
refl ective slotted sleeve which is mounted on the main shaft and cannot be replaced unless replacing the vibratory
system.
NCREMENTAL ENCODER BOARD POWER CLAMP
The power clamp encoder board B9 is connected and supplied to the main shaft encoder board. It is fi tted at 1 mm
from a code strip fi xed to the circumference of the big drive pulley, and it acquires the rotational travel direction of
rotation and absolute angular position of the big pulley at the vibratory assembly with power clamp. The output signal
passes trough the Incremental Encoder Board directly to Main Processor one
DISTANCE POTENTIOMETER
The distance potentiometer is a 10K pot. It is supplied at 3.3 VDC from the IBP box. This input voltage can be measu-
red at the IBP box X6, pin 3. The output voltage is dependent upon the defl ection of the gauge from the home position.
DIAMETER POTENTIOMETER
The diameter potentiometer is a 10K pot. It is supplied at 3.3 VDC from the main processor. This input voltage can
be measured at the IBP box X7, pin 3. The output voltage is dependent upon the rotation of the gauge from the home
position.
TRANSDUCERS
The transducers are installed in a manner that it forms a virtual transducer on each end of the shaft. This
confi guration gives the balancer greater accuracy along with minimal amount of erroneous readings. Both
measuring transducers are arranged in one plane. The transducers produce a charge output. The charge that is gene-
rated is sent back to the processor.
SONAR SENSOR
The sonar sensor is supplied and connected to X1 of the IBP
ELECTROMAGNETIC BRAKE
The PCB sends 150VDC to the Electromagnetic brake on the motor stopping the tire and wheel assembly at TDC for
the outside weight location. The voltage can be measured at X43 on the IBP box.
WEIGHT LASER POINTER
It is used to place the adhesive weights only. Weight Laser pointer is directly connected and managed on the connec-
tor X14 of the IBP box. The motion is controlled by a motor connected to X15 of the IBP.
2.5 FUNCTIONAL DESCRIPTION
The wheel balancer is designed to compute static and dynamic imbalance of car, light truck, motorcycle wheels.
Wheel is clamped to the shaft using precision centering adapters and retainers and to compute correct imbalance
values, the parameters (diameter, width, and offset) of the wheel to be balanced must be entered.
By sliding the 2D SAPE arm, the rim offeset and diameter data are entered automatically and the rim width is entered
by sonar device.
The rotating shaft is perfectly balanced and rotates on precision bearings on the shaft support. The wheels clamped
normally represent an imbalance, which creates centrifugal force and a dynamic momentum as it is spun on the balan-
cer shaft. The wheel is spun by means of a motor.
The centrifugal forces created by any imbalance are detected by the two transducers located between the shaft sup-
port and the machine frame. These transducers contain small discs of special quartz which generate electric charge
when compressed. The charge created is linearly proportional to the compression force. Centrifugal force vectors are
generated by imbalances in the rotating wheel. This causes a signal to be generated by the transducers (which pick
up only one component of the constrained forces) in the form of a periodic sine wave.
The signal is not perfectly sinusoidal, due to noises from the suspension system, which add to the signal generated by
the imbalance of the wheel. To determine acutal imbalance the signal must be fi ltered.
To fi nd wheel imbalance, the transducers signal magnitude and encoder timing are both required.
A series of timing marks on the shaft that interrupt light transmitted between two optocouplers generate a DC Square
SM HOF GEODYNA 7600 Rel.D
