grade 5 and grade 8 bolts?

[loafer]

Yes, there are many instances where a bolt is used to carry shear load directly. I generally refer to them as pinned joints, because there is little or no clamping force and it is not a static joint; rotation is permitted about the bolt axis.

The 5/16 bolt on the Hi-lift jack is another good example (I carry spares with me as they break occasionally). The bolts securing the leaf springs are another example.

I may be confused here, but isn't a bolt used to mount, say, a stock front shock on a K5 loaded in shear? The lock nut on the end of the bolt is only at like 20 ft lbs or something... seems like its loaded in shear all the time to me. I dunno.. do engineers call that something else?

j

 

[loafer]

Again, you are referring to a pinned joint, or shear pin joint. They break easy because they are designed to be a "fuse" in the drivetrain.

That is not universally true - but boy are we veering of the bolt-grade subject.
Many shear bolts are intended to carry ALL the torsional load - and do not create any useful clamping force. One example are the Grade 2 (or less) shear bolts used in augers in many types of farm equipment, snow-blowers, barn-cleaners,etc.
Another example is my 6' bush hog on my tractor. The cheaper model uses a shear-bolt where the driveshaft hooks to the input shaft of the transmission. No clamping force at all - in fact - the bolt is held in place with a crimped locknut and does not even get tightened to a point where any clamping occurrs. It is very annoying since it breaks easily - but that helps with warranty claims in the manufacutor's behalf. The more expensive model gets an adjustable slip-clutch instead of the shear-bolt.
And - since this is a Chevy or GM forum - how about the shear-shaft that drives the fuel-injection pump in all the 6.2 diesels? It too carries ALL the torsional/rotational load -and is designed to have a weak spot that will snap in two if the pump turns over too hard.