Pin for steering keeps breaking

[mrharris12 37]

Wanted to see if I’m crazy or if anyone has had this issue: hair pin kept breaking that attaches the fan gear to the steering block on 418. 
 

I have been cutting grass just fine all year and then all of the sudden 3 break in a matter of like 30 minutes worth of cutting. The only thing I did was put grease in the zerk on the steering block.

 

but I was wondering does the type of pin matter? I believe before this year it had a cotter pin, then earlier this year I had the bushing in the steering block replaced and probably used a hair pin. Then this past week 3 break and I am not sure what has happened. Currently I put a cotter pin but didnt have time to drive with it. Anyone able to explain?

[gwest_ca-(File Mod) 12,336]

Item #18 part number 932035?

https://www.partstree.com/models/41-18ke01-418-c-toro-garden-tractor-1987/front-axle-and-steering-6/

A bit of searching comes up with 3/16" x 1-1/4" long cotter pin. That is a hefty pin.

Make sure you do not have it shimmed too tight. There should be a few thousands of clearance between the gear teeth from full left to full right. No clearance and something has to give.

[ri702bill 12,430]

The fan gear to shaft connection is a classic "double shear" scenario. The present cotter pin gets twisted by the forces at the ends - one up, the other down and it reverses as you turn the tractor the other way until the material fails and the pin breaks into 3 piees due to metal fatigue. It is clearly being overloaded and not the proper fastener for the job....

My suggestion is to carefully drill out the hole thru both to 1/4 inch and upgrade to a spring pin or better yet, a coiled pin. If you go with the spring pin (aka tension pin), be sure to install it in the proper orientation. That would be with the split line in the direction of rotation, not 90 degrees off. The coiled pin has no orientation and is the better choice.

[953 nut 67,318]

Many Wheel Horse steering applications use two Roll Pins, one inside the other. In the case of a GT-14 they are 5/16  X  1.5  with a 3/16  X  3/16 driven inside it.

[ri702bill 12,430]

I can attest to that on my 854. It only had the 5/16 one installed incorrectly, it broke. Finally switched to an 8 MM coiled pin - better fit since the shaft hole had sterted to wallow out.

Edited 9 hours ago by ri702bill

[pfrederi 20,834]

I have a lot of WHs all use the cotter pin never broke one..

[ri702bill 12,430]

If there is movement allowed by having less than a snug fit between the pin and the hole(s), that sets up the failure mode flexing the pin....

[Lee1977 7,698]

7 hours ago, ri702bill said:

If there is movement allowed by having less than a snug fit between the pin and the hole(s), that sets up the failure mode flexing the pin....

If the gears are too tight that also a proble hard steering and an extra load on that cotter pin. 

The fan gear is cast iron not machined the best you will ever get taking out the play in the steering is about an inch to !" to 1 1/4" play in the steering wheel.