cammed ascender

[grv77]

Hey everyone,
Im upgrading my lanyard and instead of using a beckett
bend knot as a means of adjustment i got a gibbs ascender.
Some texts say to replace the locking pin with a lock nut and
bolt. I wanted to get some advice before just simply putting ordinary hardware in the gibbs.
Thanks

 

[southsoundtree]

I got a grade 8 bolt and ny-lock nut. Loctite is another option. Been good to me. One grade 8 bolt is cheap and readily available. Maybe overkill, but better than underkill.

 

[Tony]

Sean is correct, use a grade 8 bolt. It has more to do with longevity as the cam rotates around the shaft of the bolt, than the physical shearing strength of the bolt.

In the attached pic from Gibb's web site you can clearly see the 5 tick marks on the head of the bolt indicating a grade 8 bolt.

It is vital you use a locking nut and do not over-tighten and compress the shell of the ascender. Lock-tight will work, but a nylon locking is by fay the better option for arborists.

If you have to remove the nut more than two or three times replace it as the "locking" feature is diminished every time the nut is turned.

Good question I appreciate you caution.

Tony

 

[Tom Dunlap]

When I used a Gibbs I replaced the pin with a socket head cap screw. The shcs has a round head that drops inside the plastic Side piece and mates flush with the shell of the ascender. This is better than a machine bolt where the load is placed on the plastic.

 

[Tom Dunlap]

Another lanyard idea and bolt talk too:

http://www.treebuzz.com/forum/showflat.p...true#Post233423


http://www.treebuzz.com/forum/showflat.p...true#Post131389

 

[SingleJack]

[ QUOTE ]
Sean is correct, use a grade 8 bolt. It has more to do with longevity as the cam rotates around the shaft of the bolt, than the physical shearing strength of the bolt.

In the attached pic from Gibb's web site you can clearly see the 5 tick marks on the head of the bolt indicating a grade 8 bolt.

It is vital you use a locking nut and do not over-tighten and compress the shell of the ascender. Lock-tight will work, but a nylon locking is by fay the better option for arborists.

If you have to remove the nut more than two or three times replace it as the "locking" feature is diminished every time the nut is turned.

Good question I appreciate you caution.

Tony

[/ QUOTE ]

Just a minor clarification: SAE Grade 8 bolts have <u>6 tick</u> marks. SAE Grade 7 bolts (rarely seen) have 5 tick marks.

Reference: http://www.engineershandbook.com/Tables/boltgrades.htm

 

[TimberJack]

Wouldn't a stainless steel bolt be an even better option?

 

[Tom Dunlap]

A socket head cap screw solves the issue the best. Plenty strong too. Stainless might be a good solution..but why the expense?

If the shear strength is the consideration I think that a grade 3 might be plenty strong...but don't quote me.

Find out what the shear strength is for the push button spring release pin that comes with the Gibb's and match it.

 

[TimberJack]

The expense of a stainless steel bolt is pretty minimal.

 

[TimberJack]

When my friend got his gibbs it came with a bolt and the pin.