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Control rod.
When you move the forward thrust lever, the force goes through the reverse thrust lever down to the thrust lever crank. The forward thrust lever and crank turn on the same shaft, but only connect together with the reverse thrust lever. The crank connects to the ASM brake with the control rod. The ASM brake turns the rotor of the TLA resolver. The resolver sends a thrust resolver angle (TRA) signal to the EEC.
When the forward thrust lever is not at idle, the lever latch holds the reverse thrust lever down. When the forward thrust lever is at idle, you can raise the reverse thrust lever. When the reverse thrust lever is up, the latch holds the forward thrust lever at idle.
EFFECTIVITY
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Autothrottle Assembly
These are the four components of the autothrottle (A/T) assembly:
*
ASM
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ASM gearbox
*
TLA resolver
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ASM brake.
The ASM turns a shaft in the A/T assembly through the ASM gearbox. When the shaft turns, it turns the ASM brake. The ASM brake turns the rotor of the TLA resolver and, at the same time moves the thrust lever.
ASM Brake
The ASM brake is a spring-loaded clutch assembly. These are its functions:
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Mechanical connection to the thrust lever
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Friction source for the thrust lever
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Mechanical connection to the TLA resolver
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Mechanical connection to the A/T assembly shaft
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T/R control interface.
The ASM brake connects to the A/T assembly shaft with a clutch. This permits you to manually override ASM inputs.
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ENGINE CONTROLS -THRUST LEVER & AUTOTHROTTLE ASSEMBLY -FUNCTIONAL DESCRIPTION
The T/R interlock actuator (not shown) keeps the ASM brake from turning beyond reverse idle until the thrust reverser deploys.
TLA-TRA Relationship
When the thrust lever is at idle, the TRA is approximately 34 degrees. As you move the thrust lever forward, the forward TLA increases. At full forward TLA, the TRA is approximately 85 degrees.
When you raise the reverse thrust lever, the reverse TLA increases. At full reverse TLA, the TRA is approximately 5 degrees. The flat spot in the reverse TRA curve is where the reverse thrust lever closes reverser control switches without increasing engine power.
Engine power increases between approximately 34 and 85 degrees TRA in forward thrust. Engine power increases between approximately 24 and 5 degrees TRA in reverse thrust.
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ENGINE CONTROLS -THRUST LEVER & AUTOTHROTTLE ASSEMBLY -FUNCTIONAL DESCRIPTION
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ENGINE CONTROLS -TLA RESOLVER
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