I have a model 70 plow that I really like except there are no trips on it - just solid shanks. My assumption is that bolts are supposed to shear if you hit a rock. All of the bolts on mine are grade 5 and when plowing yesterday, the upper bolt would shear (happened three times) and it actually bent the bracket at the lower bolt when the upper part of the shank was forced by the end of the frame.
Which bolt is supposed to shear and what grade bolts are correct? The plow was in "like new" condition when I bought it with the original decals on it so I don't think it had ever had much use.
Thanks in advance for any help or advice.