General Maintenance and Troubleshooting
SM 6495, Rev. 7, December 2008 3-15
3.3. Troubleshooting (General)
Table 3-1 presents a list of troubleshooting concerns and their solutions.
Table 3-1 - Troubleshooting Table for Model 95 Gate Mechanism
CONDITION SOLUTION
1. Gate arm remains in a horizontal position when
track is unoccupied.
a. Ensure gate mechanism is receiving correct
supply voltage. Ensure #1 contact is closed.
b. Ensure relay is operational, energized.
c. Ensure gold nut on test link is closed.
d. Ensure circuit breaker is closed.
2. Gate arm descent too fast or too slow. a. Adjust snub resistor on electrical assembly.
b. Ensure counterweights are set properly.
3. The gate arm drops below the horizontal position. a. Adjust the horizontal buffer spring.
b. Ensure torque is set correctly on gate
mechanism.
4. Motor does not drive gate arm through power-
down portion of descent.
a. Check No. 3 contact on circuit controller, make
sure it is closed 46-93°.
b. Check power down module on 12-volt systems
(Refer to Section
3.3.1) or power down relay on
24-volt systems (Refer to Section
3.3.2).
5. Grounds in the Gearmotor. Blow the brush dust out of the gearmotor (Refer to
Section
3.2.10).
3.3.1. Testing and Troubleshooting the Power Down Module for 12-Volt Systems
The following procedure describes the steps taken to test the power down module (Figure 5-10 or
Figure 5-11, Item 275).
1. With arm in the clear position, place voltmeter on terminals 6B(-) and 3A(+). The meter should
read approximately 0 volts (refer to 5B (refer to
Figure 2-2, Figure 2-3, and Figure 2-5 for terminal
locations for terminal locations).
2. With arm descending, meter should read 12VDC nom. (system voltage).
3. When arm reaches the 45° point (halfway down), the meter should return to 0 volts.
If this test resulted in incorrect readings, check the following:
1. Check the No. 3 contact for proper adjustment.
2. Check the limit resistor to ensure it is not open.
3. Check for proper wiring (refer to
Figure 2-2, Figure 2-3, and Figure 2-5).
4. If no problems are found with items one through three above, then replace the Power Down
Module.
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