Am I the only one that finds this strange?

prof_fate · 04-20-2011, 05:55 PM

On my van that we used to tow up to 2000lbs and on many previous vehicles with receiver hitches I've seen the same thing - a pin that holds the receiver in and takes the entire pulling (or pushing load) of the hitch.

Now on my new setup I had to get a 2 5/16 ball with a 1 1/4" shank, the bits that hang on the receiver weigh a good 50 or 60 lbs, going to tow mebbe 7000 lbs....and the only real connection is the same size pin, perhaps 1/2" diameter, that I've seen on light duty hitches.

Is there some engineering magic on that pin? I've seen balls and hitches with all sorts of weight ratings and I've seen spare pins - and never a rating on them!

Am I the only one that feels this is strange?

**Herk7769** · 04-20-2011, 06:13 PM

Other than that pin is hardened steel and the hitch is soft steel, no.

My hitch shank pin hole shows wear (slightly elongated) from towing in just 1 1/2 years. The pin looks brand new.

backin15 · 04-20-2011, 06:47 PM

I often think of all that weight riding on that pin when I am towing up a steep hill. But it is a hardened pin and since the gap between the reciever and the shank is so small it would take an increadible amount of force to shear.

leencharlotte · 04-20-2011, 08:54 PM

I have been wondering the same thing... i just try to not think about that little skinny piece of steel holds all that together... lol

04eddie · 04-23-2011, 07:35 AM

Has any one ever seen one sheared. I have seen a couple bent before but they were bent when trying to pull out a stuck truck not during towing. I think when you are towing there is 400 or 500 lbs pushing down from tongue weight so the ball mount wont move enough to cause a shearing effect. just my thoughts

08flagvlite · 04-23-2011, 10:21 AM

You can buy replacement pins with a locking end that are case hardened steel, and weight rated for 5000 lbs. aftermarket- I think I got mine at Advance Auto Parts. Works very well; had it almost 4 years, and still looks just like I bought it. I think it was made by Reese, but not positive. Randy

zx5chris · 05-04-2011, 11:33 PM

Don't forget about the toque that is applied to the verticle load. The retaining pin doesn't have to deal with this additional load, and the pins usually solid. so I don't really think of this issue.

prof_fate · 05-05-2011, 07:32 AM

1/2 dozen 9/16 grade 8 bolts to hold the hitch to the frame
4 more to hold the ball part of the trailer to the toungue
2 even larger bolts hold the two pieces together that make up the ball and receiver assembly, and mine came with shims to be sure there was no freeplay in there.
a 1" shank ball isn't strong enough, so you gotta get a 1 1/4" shank ball.
And then you gotta bolt this together at hundred of pounds of torque.

The only thing really keeping the trailer attached is a 1/2" pin that isn't torqued in at all, rattles in it's holes and weighs less than one of the bigger nuts.

If the pin is strong enough then everything else seems to be overkill.

Quote:

Originally Posted by zx5chris

Don't forget about the toque that is applied to the verticle load. The retaining pin doesn't have to deal with this additional load, and the pins usually solid. so I don't really think of this issue.

08flagvlite · 05-05-2011, 11:40 AM

The pin only comes into play from horizontal pulling and pushing from power and braking applied from your tow vehicle. This is why that pin is not necessarily large, IMO. Randy

youroo · 05-05-2011, 11:59 AM

Quote:

Originally Posted by prof_fate

On my van that we used to tow up to 2000lbs and on many previous vehicles with receiver hitches I've seen the same thing - a pin that holds the receiver in and takes the entire pulling (or pushing load) of the hitch.

Now on my new setup I had to get a 2 5/16 ball with a 1 1/4" shank, the bits that hang on the receiver weigh a good 50 or 60 lbs, going to tow mebbe 7000 lbs....and the only real connection is the same size pin, perhaps 1/2" diameter, that I've seen on light duty hitches.

Is there some engineering magic on that pin? I've seen balls and hitches with all sorts of weight ratings and I've seen spare pins - and never a rating on them!

Am I the only one that feels this is strange?

The pin diameter is 5/8 on the Cat. 3-4 5 hitches! Youroo!!

flyrotor · 05-05-2011, 01:57 PM

I have never heard of an issue with a pin shear, even in crashes. I have seen instances where the 2" shank has sheared from an impact, trailer balls that have sheared, trailer tongues twisted and wrapped into a new shape, trailer axles pulled from underneath the trailer, but never a sheared pin.

thebrakeman · 05-13-2011, 08:57 AM

Quote:

Originally Posted by prof_fate

1/2 dozen 9/16 grade 8 bolts to hold the hitch to the frame
4 more to hold the ball part of the trailer to the toungue
2 even larger bolts hold the two pieces together that make up the ball and receiver assembly, and mine came with shims to be sure there was no freeplay in there.
a 1" shank ball isn't strong enough, so you gotta get a 1 1/4" shank ball.
And then you gotta bolt this together at hundred of pounds of torque.

The only thing really keeping the trailer attached is a 1/2" pin that isn't torqued in at all, rattles in it's holes and weighs less than one of the bigger nuts.

If the pin is strong enough then everything else seems to be overkill.

The typical bent pin is such a stupid easy part to make, that it would be silly to make them at lower grades. So they probably make them for the largest pull-behind trailers (20,000 lbs?). To make the same geometry pin with a material grade only strong enough for a 10,000 lbs trailer, would drive up inventory costs, probably be a grade with imperfections, and likely only save us $0.25. Of course there is a smaller pin, for use in the 1¼" Class 2 hitches.

As far as the other fasteners in the system being overkill, I disagree.

That bent pin is placed in pure shear. There is no tension or compression loading on that pin. Conversely, the other fasteners you mentioned are threaded joints, place in tention, to produce clamping load. Any steel fastener or pin can take far more shear force than tension.

I remember an axle joint I was working on (at my job), where you had four (4) 3/8" threaded studs holding the brake assy to the axle flange. During some extreme powertrain durability tests (forward/reverse transmission cycling), the drivers could hear the brake slipping thru the axle joint, and "clunking" against the fasteners. The 4-bolt joint was not strong enough to prevent the slippage...tightening the bolts further would break the bolts. But the impact from the holes banging the bolts in shear wasn't even close to damaging them. The noise was the complaint, not damaged bolts. The solution was to increase the bolt size and bolt pattern diameter. Not to protect the bolts from shear, but to allow the bolts to take a higher torque, and prevent the slippage in the first place.

The_Stuff · 05-13-2011, 10:42 PM

This is what happens when you try to pull start a semi :P (NO, IT WAS NOT ME)

So that shows how much strength that the pins have! I cant find the pin picture but it was just slightly bent.

ALSO stay away from the pins that have the little swivel part at the end that is supposed to hold it in. well they dont and we lost a sled trailer once..

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