I notice that small dozers have a set ripper angle and large ones have an adjustable angle. Why is that and what is the proper angle to have the ripper at for ripping. Do larger rippers have adjustable angles just so you can wiggle it when you hit a hard spot? Also when I was a child my father would tell me storys of working in Alaska and ripping ice/frost/frozen ground and pulling up the ripper and having it be so hot that it was glowing red. He clamed it was quite a sight at night. Has anyone ever seen such a thing?
I have wondered the same thing about smaller tractors at least to the D6 size having a 4 barrel ripper.Here's my take. The shank angle of course changes with the arc of the ripper, on the smaller rippers with short shanks the arc is alot less than say a D8 with 4' shanks so the angle change is less plus the smaller machines lack the power and weight to deal with really tough material anyway so why go to the expense of a 4 barrel ripper. The parrelogram or 4 barrel ripper on larger machines allows the operator to increase the angle of attack of the points to penetrate hard or rocky material then adjust the shank angle foreward to ripp.This is also usefull when prying out hard spots. I usually run the shanks a little foreward from vertical to keep the point breaking the way for the rest of the shank. I've seen hot enough points to burn your hand but not glowing.
Not all large dozers have 4 barrel rippers. They are alot more expensive, but there is no better way to rip. You really don't need an adjustable ripper on a smaller tractor because smaller tractors tend to rip mainly just hard dirt as opposed to larger tractors ripping rock.
The above posts have pretty well summed it up in my opinion. As far as ripping ice or perma frost til the tooth turned red I'm having a hard time to believe it. Not saying it didn't happen, just skeptical. I've never ripped permafrost or ice but have ripped a lot of frost. The point does get hot but not that hot. I've seen it sizzle if you spit on it. If it turned red wouldn't it lose its structural competence?
I agree with Rino and DPete. Now with a big dozer there is more to "proper angle". If I'm not in harder ground and penetration isn't an issue I always keep the ripper angled this "/ " with the tooth close to the tracks. That way you get the most wear out of the tooth, it stays sharp, and you are ripping/pulling the ground up not just making "trenches". As it wears you may have to move it more vertical but it should be kept at that angel as much as possible. As the ground gets harder you have to move the tooth away from the tracks like this "\", but once you get penetration it should be moved to as much vertical to like this "/" as you can without lifting the back of the dozer off the ground or the rippers not climbing out of the ground. There will be times when the ground is so hard that you can't get any bite without having the ripper as far away from the tracks as possible and you can't move it towards the tracks at all.