Question for you machinists on hardened metal

[dpinvidic]

My son has Atwood leveling jacks.
One time he bottomed out his rig, and broke a pin inside the jack.
When this pin breaks, the jack drops down because the inside threaded shaft is now disconnected.

ANYWAY, I have made different replacement pins for him using cold rolled steel, and water hardening drill rod. The pin in this jack still continues to break about once a year on average. The other three jacks have never broken a pin.

Any suggestions on a different material to use for a replacement pin?
Atwood will not sell parts, only a complete jack.

Regards,

Dan

[LETMGROW]

Originally Posted by dpinvidic

My son has Atwood leveling jacks.
One time he bottomed out his rig, and broke a pin inside the jack.
When this pin breaks, the jack drops down because the inside threaded shaft is now disconnected.

ANYWAY, I have made different replacement pins for him using cold rolled steel, and water hardening drill rod. The pin in this jack still continues to break about once a year on average. The other three jacks have never broken a pin.

Any suggestions on a different material to use for a replacement pin?
Atwood will not sell parts, only a complete jack.

Regards,

Dan

What size is the pin? I have fixed similar problemchilds using the smooth part of a grade 8 bolt. Cut the bolt to size and use a sharp prick punch to dimple the bolt ( now a pin ) and apply a small amount of "loc-tite" to the pin before driving it into place.
Worth a try.
Lynn

[Hikerdogs]

You might try ASME dowel pins or dowel pin stock:

McMaster-Carr

There are also stronger bolts available. The extreme strength grade 9 bolt uses steel with a tensile strength of 180,000 psi while a grade 8 bolt uses steel with a tensile strength of 150,000 psi.

McMaster-Carr

[MotorPro]

Don't use grade 9 bolts. While they have high tensile strength they are brittle and will shatter. They are often used as shear pins.

[scrapperjohn]

Hardened pins are way too brittle.
What dia. is pin, how long?
Think trailer hitch pin for receiver.
Lock pin for Jack stands.
Cold rolled may be a bit soft & get gouged up.
Case hardened may work.
Shoulder bolt should work.
Take a GOOD look at other pins, try to match material,
Good luck

[jacwjames]

Go to a hydraulic repair shop and they may be able to help you. Show them what has happened and see what they have that may help to fix you.

[Steady_Rest]

Did you temper the W-1 drill rod after water quenching. If not it would be at its maximum hardness and be prone to easily break. If you have a vocational school nearby they can test the hardness etc. of an original pin. They may also offer advice when you clearly describe the application. They could even make several pins for you for a nominal fee. I would not think high hardness would be a property you need for the application, unless the pin is submitted to high bearing wear. I would avoid high carbon steels like drill rod and look to alloyed steels with low to medium carbon.
Steels such as 4130, 4140 4340 are common for many high strength applications from pins to axles, and these steels are widely used in making hs bolts. There are bolt charts on line that show the properties of various grade bolts and the steel used for each.


For example:
https://www.google.com/url?sa=t&rct=...FR3KzifGcfqd6A

[dpinvidic]

Wow, lots of good info and questions.

For some reason the pin is .224 dia. X .60 So I have been turning down .250 drill rod. I can't find off-the shelf dowels in that diameter.

My assumption is that it is a "Shear Pin" for safety. but I am not sure why it keeps breaking. that is why I tried both cold rolled and air hardening rod.
NO...never tried to case harden it.

I have actually not seen the jacks, my son brought me the first broken pin, and I have been making replacements based on it.

I think I will ask him to take the jack off so I can see the details. Maybe the holes are no longer square with the sides, and it might now be acting like a shear with the edges of the hole getting all the pressure.

Hope I did not do more harm with the hardened pin

SteadyRest...with that name, you must know your stuff.....I will get a 1/4 bolt and use the unthreaded portion to make some new pins in addition to inspecting the hole.

Thanks,

Dan

[Steady_Rest]

I spent 40 years in various machine shops but still have a lot to learn. You seem to be approaching this problem very well, the same as I would. I also agree having the jack would be very beneficial, it may have a story to tell. You will succeed because of your perseverance.

Kevin

[alank]

I'm not familiar with the Atwood jacks, but just from what I read here, taking the jack off for inspection would be a good idea. I wonder if when bottomed out, some other damage was done beside breaking the pin. I'm thinking of the threaded shaft or other component being tweaked so there is excessive resistance to the shaft turning causing the pins you're making to break. See if the jacking operation operates freely.

[Guidedbomb]

I fought those Level Leg jack problems for two years. Atwood was of no help. The system is beating itself to pieces by not sensing enough current spike when the jack hits the end of jack travel when retracted and engages the mechanical clutch. Since the spike is too small, the motor keeps driving and eventually shears the pin or breaks one of the gears. The failure occurs on retraction not from overload on the jack.

I removed the motors and took them apart. I found the brushes were not making good electrical contact and were therefore not pulling enough current to shut the power off when the mechanical clutch was engaged. The fix was simple. Cleaned up the copper/brush interface with sandpaper. The jacks now retract and shut down on the first clutch engagement.

[gruelens]

I might replace the problem pin with a drill bit. Select bit with a diameter that matches the pin's diameter. Cut the drill bit to length with a dremel.

Note: this should get you going and be affordable. However, will not protect you from over torque situations like original pin.

[chboone]

It may be that the limit switches are off from the first time the pin broke. If they are off the motor will keep running when the jack reaches it travel limit, most likely when it's retracting breaking the pin.

[Old-Biscuit]

With 5vr hitched up run driven leg down until fully extended.
Paint the top 1" RED
Then run until fully retracted..extend it 1" and paint bottom 1" RED

Then tell son.......stop running the legs past the RED marks


Pg. 36 landing gear internal components
https://bryantrv.com/docs2/docs/HDW04.pdf