Typical Relay
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| Illustration 1 | g00564606 |
Typical relay | |
Relays control the operation of some alert indicators within the machine monitor. Relays are two-state devices. The two states are Closed relays and Open relays.
Closed - The closed contacts of the relay connect the control input to +battery or ground.
Open - The Open contacts of the relay do not connect the control input anywhere. The input is floating.
Lamp Test Relay
The machine monitoring system uses the normally open contacts (87) and (30) of the lamp test relay. The key start switch controls the lamp test relay. During normal operation, contact (87) is open and the lamp test relay is deactuated.
When the key start switch is in the START position, the relay is actuated and contact (87) closes to ground. The grounded contact (87) provides a path to ground. The path to ground is for all of the alert indicators within the machine monitor except the indicators for the turn signals. Also at this time, the affected alert indicators turn ON. This provides a lamp test function which allows the operator to check the operation of the alert indicators.
Belt Tension Control Relay
The machine monitoring system uses the normally closed contacts (30) and (87a) of the belt tension control relay. The belt tension buffer controls the belt tension control relay. During normal operation, contact (30) is open and the belt tension control relay is actuated. When the belt tension system is NOT operating properly, the relay is deactuated and contact (30) closes to ground.
Grounded contact (30) provides a path to ground for the belt tension indicator and the action alarm. The illumination of the belt tension indicator and the sounding of the action alarm notifies the operator that the pressure in the belt tensioner cylinder is not correct.
Note: For setpoint information for the belt tension buffer, see the topic "Belt Tension Buffer" in this module.
Right Turn Relay and Left Turn Relay
The Turn/Hazard/Horn Switch controls the right turn relay and the left turn relay. Also, the Turn/Hazard/Horn Switch controls the ground signal (turn common) to the turn signal indicators. The operation of the relays, switches, and indicators is described in the following paragraphs.
When the turn signal lever is in position for a RIGHT turn, the following conditions will occur:
- Ground (turn common) is provided to both turn signal indicators.
- The right turn relay remains deactivated and the flasher signal remains at the indicator for the right turn signal. Therefore, the indicator for the right turn signal FLASHES.
- The left turn relay is actuated. This removes the flasher signal from the indicator. Also at this time, a +battery signal is applied to the indicator. Therefore, the left turn signal is ON continuously.
When the turn signal lever is in position for a LEFT turn, the following conditions will occur:
- Ground (turn common) is provided to both turn signal indicators.
- The left turn relay remains deactivated and the flasher signal remains at the indicator for the right turn signal. Therefore, the indicator for the left turn signal FLASHES.
- The right turn relay is actuated. This removes the flasher signal from the indicator. Also at this time, a +battery signal is applied to the indicator. Therefore, the right turn signal is ON continuously.
When the turn signal lever is in the NEUTRAL position, both the right and the left turn relays are deactivated. Also at this time, the relays provide a flasher signal to both turn signal indicators. The turn signal indicators do not flash because the switch for the turn signal is not providing ground (turn common) to the indicators at this time.
When the turn signal lever is in the HAZARD position, the right and left turn relays are deactivated. A flasher signal is provided to both the turn signal indicators (left and right). Also at this time, the switch for the turn signal provides ground (turn common) to both turn signal indicators. Therefore, both of the turn signal indicators will flash.