737: what is this flipping rotating spinning thing and why?
Posted by mysteryofthefieryeye@reddit | flying | View on Reddit | 36 comments
Watching a take-off video and every so often, on either side of the throttles, a fidget spinner goes into action.
It delights me lol. What is it, pleaes, and what is it for and what if someone's knee or hand gets in the way and interferes with it?
peter662@reddit
That’s trim wheel for the elevator trim.
mysteryofthefieryeye@reddit (OP)
Ohhhh nice, thank you!! I just plugged your comment into youtube and watched a video explaining it and showing it (though the trim was done manually and I'm guessing on the 737 it was more automatic).
Th3catspyjamas@reddit
It's both. The autopilot will adjust it and it will spin. It can also be adjusted manually when hand flying. It can be controlled via a switch on the yoke that runs a motor and spins the wheel/adjusts the trim. It can also be moved by hand, there is a lever on a spring that folds out perpendicular allowing for easier cranking as well as for additional play past the allowable limit of the motor.
aeroxan@reddit
The physical link is a failsafe. If the motor fails, you can still trim the plane. If the trim starts running away, you can physically stop it.
12kVStr8tothenips@reddit
Technically the stab trim but yeah.
retiredaaer@reddit
The white stripes are there to show that the trim wheel is moving and how fast it’s moving in case of runaway trim.
mysteryofthefieryeye@reddit (OP)
I was just reading about runaway trim. Great comment supplying new info for me, thank you!
PM_ME_YOUR_PITOTTUBE@reddit
The hand breaker.
ChuckS117@reddit
the knee destroyer
PM_ME_YOUR_FOQA@reddit
That’s the trim wheel. It’s electric, and if need be manual.
mysteryofthefieryeye@reddit (OP)
just watched a small plane video with the manual version and it cleared up a lot of things. fascinating. thank you!
pilotshashi@reddit
Trim 🫳🏼
mig82au@reddit
"Flying
This community is for discussion among pilots, students, instructors and aviation professionals."
mysteryofthefieryeye@reddit (OP)
Can one not be a student of flying by simply appreciating the beauty of engineering and physics (and flight deck fidget spinners)?
mig82au@reddit
No
Reiia@reddit
Knee Breaker
But jokes and pain aside, thats the manual trim wheel...
Square-Armadillo-245@reddit
This is the penis torque machine. Currently captain 737 and it torques my penis well.
voretaq7@reddit
That’s the trim wheel.
It’s there to remind you to stow the big crank on the trim wheel before engaging the autopilot (because if you don’t it beats your knee something fierce).
Also it makes a very satisfying clickety-clackety noise to remind you something is moving the trim and if you don’t think that should be happening you should hit the autopilot disconnect (or the copilot).
Better-Addendum2674@reddit
Oh trim
Hung_Like_A_Mare@reddit
I’ve had to use it after we had a trim fail. Speed trim still worked and startled us thinking it was a runaway.
Anyway, yeah it wasn’t much different than trimming my Cessna. Just with my left hand instead of my right.
Big-Carpenter7921@reddit
Trim
SATSewerTube@reddit
Too much shucka shucka = Ryanair landing
Too little shucka shucka = Ryanair landing
alphawonka@reddit
Whoosh whoosh whoosh whoosh — pause — whoosh whoosh whoosh
runway31@reddit
Trim wheel. Speed trim system automatically moves stabilizer to assist with trim state of the airplane
flyingron@reddit
Hoist up the thing.
Batten down the whatsis.
What's this thing spinning?
Somebody should stop it.
ObiWang38@reddit
The knee knocker
poser765@reddit
Trim-o-matic. By cuisinart.
ApoTHICCary@reddit
As my instructor would tell, “MORE TRIM!”
MaCPilot75@reddit
The 73 knee annihilator.
Belowmda@reddit
'Tis the Boeing patented knee bruiser. Doesn't seem to achieve much else...
In all seriousness it is the trim wheel. Rotates when either the automatic or manual trim is activated. Also used to manually set the trim in certain failures (from a very distant memory). Noisy in the classic, can't speak for the NG or Max.
doom_pizza@reddit
Still noisy in the NG and max.
DragginSPADE@reddit
Still noisy in the NG.
BrtFrkwr@reddit
That's the clankety-clank. A piece of living aviation history. A true relic. A fossil, as it were. Its uncontrollable spinning and impossible to ignore noise lets everyone in earshot know there's a runaway stabilizer.
Salavar1@reddit
Manual trim wheel for the Hstab.
britishmetric144@reddit
The wheel is part of the trim system.
The trim system controls the elevator on the tail of the aircraft, which when moved, causes the nose of the aircraft to rise or drop.
This allows the aircraft to climb or descend without the pilots having to maintain constant pressure on the yoke at all times. (It takes a lot of physical effort to move the yoke!)
rFlyingTower@reddit
This is a copy of the original post body for posterity:
Watching a take-off video and every so often, on either side of the throttles, a fidget spinner goes into action.
It delights me lol. What is it, pleaes, and what is it for and what if someone's knee or hand gets in the way and interferes with it?
Please downvote this comment until it collapses.
Questions about this comment? Please see this wiki post before contacting the mods.
I am a bot, and this action was performed automatically. If you have any questions, please contact the mods of this subreddit.