Author Topic: Cadet parking brake  (Read 3210 times)

Bill Poynter

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Cadet parking brake
« on: August 07, 2012, 07:38:05 PM »
Does anyone know if a parking brake was ever an option on the Cadet?  The reason I ask is my curiosity regarding the purpose of the disc welded near the center of the shaft of the master cylinder pushrods.  I've attached a photo to illustrate what I'm talking about.  This is the spot where the radio controlled brake actuator engages the pushrods on the PQ series.  I don't know of any reason for the Cadets to have this other than for a parking brake.  Any ideas?

Culver Dreamer

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Re: Cadet parking brake
« Reply #1 on: August 08, 2012, 01:24:08 AM »
  Hi Bill:  I wish I had a picture from the front side but this is all I have, and I won't be around my airplane for at least a month. Is it possable that the "welded disk" you show has anything to do with the springs shown close to where the brake actuator attaches. ( follow the rod from the master cyclinder out towards the right of the picture)
 Mark (The Culver Dreamer)

Bill Poynter

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Re: Cadet parking brake
« Reply #2 on: August 08, 2012, 09:04:22 AM »
The rubber boots appear to be missing from the master cylinders in the photo.  Neither of my cadets had the spring or the aluminum looking collar in front of the spring.  Any idea what they are for? My only guess would be to retain the aft end of the rubber boot.
« Last Edit: August 08, 2012, 09:06:52 AM by Bill Poynter »

Culver Dreamer

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Re: Cadet parking brake
« Reply #3 on: August 08, 2012, 11:27:15 AM »
Sorry Bill I have no idea what the springs are for, and I have to agree the master cyclinders look like they are missing their dust boots.
Mark

Brett Lovett

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Re: Cadet parking brake
« Reply #4 on: August 08, 2012, 10:56:51 PM »
My cadet has had these replaced, so I've never gotten a good look at the original master cylinders.  I understand however that they were adapted from an automobile application (1937 Chrysler?).  Is it possible the welded disc on the pushrod served a purpose when installed in the Chrysler?  The type certificate data sheet does show item 307 for a parking brake at 1 lb. with an arm of -3, but I've never seen any other info on it.

Bill Poynter

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Re: Cadet parking brake
« Reply #5 on: August 09, 2012, 09:43:58 AM »
I knew I had seen a reference to a parking brake somewhere. 

I don't think the pushrod was an automotive product.  It appears to have been fabricated by Culver to adapt the automotive master cylinder to the rudder pedal.

If you look at the illustration on page 29 of the PQ8-A Erection and Maintenance Instructions, you'll see how this disc could have been used to interface the radio controlled brakes to the pilot operated ones.  It may not have been exactly the same pushrod, but it was probably similar.