I operate much smaller equipment than a lot of you guys on this forum. I have a bobcat, skiploader, and backhoe and occasionally rent larger equipment to do jobs. For the past week I have been doing a remove and re-compact job for an apartment building using a D6N and a John Deere 544J 3 yard loader. We have to go down 5 feet and the lot size is 230 X 110 and surrounded by apartments on three sides and the street in front. So we are removing dirt from one half, storing it on the other side, and then replacing and compacting etc. Due to shrinkage and the fact that the lot has to be raised 2 feet in the back and 1 foot in the front, we have to bring in a lot of dirt. Although cramped for space, this is a fun job. Both machines (rentals) are fairly new with about 1500 hours each. I am having the most fun on the dozer. I have never used one of the newer ones and find them fairly easy to adjust to. I had a thought though. When backing up to push another load, I would use 3rd gear and it seems like it would get rumbling along pretty fast. What would happen if a guy had a heart attack while operating one of these machines. With the decelerator and the brake being the only thing to slow down or stop one of these things. It would make quite a mess before it finally got to something to stop it. I thought of this as I was backing toward the street. If it went uncontrolled in 3rd gear, it would wipe out everything in the street and get who knows how far into the apartment across the street before it stopped. Has this ever happened before? The Deere has a cab with A/C and the dozer doesn't. The temps have been hovering around 100 degrees. The Deere certainly is comfortable to operate, but the dozer is more fun.
This reminds me, an old employer of mine once told a story about how he was running a 555 in a field, and jumped off the machine to do whatever, He twisted his ankle when he hit the ground. Went about what he was going to do, got back on the machine and took off. All of a sudden he woke up and was all the way across the field, and had no idea how he got that far. Turns out it had hurt pretty bad, and he wound up passing out from the pain. In 2st forward, full throttle. Lucky he was in a field!!!!!!!!!!!!
Not to change the subject but I had it taught to me that the only time we use 3rd gear was in an emergency. The only time I use it is when it's starting to rain and I need to get it sealed and drained or when I'm tracking a long, straight distance. Then I'll throttle down so the tracks aren't slapping so bad. It's very hard on the undercarraige and with clutch steering it's pretty jerky if you have to make an adjustment. I still feel guilty and like I'm being watched the few times I do use 3rd.
Not to hijack the thread but what biggixxerjim was talking about reminded me of that video on youtube. http://www.youtube.com/watch?v=6fA9jCtHMEg
Its a good point Bob. This has happened (heart attack) to a farmer here on a combine harvester...there has also been more than a few farmers get their head down in a graveyard shift to wake up with a few miles of fence wrapped around the draper front. One thing I have noticed is that invariably when dead man switches or clutches are fitted it is often the case that human beings will bypass this safety device.
I've seen a lot of operators that seemed to be dead till they hit something, brain dead that is. Foreman on the one job I was on last summer wondered why I wasn't chasing pans in third forward and backing up to catch the next one in third reverse. Long silence and a thousand yard stare on my part, then, "this is as close to a rock job as one can get and still move a little muck with three scrapers. Do you know how old I am?" We're on a small housing development project and he thought we were building Hoover Dam I guess.
Man, I never use 3rd gear unless I am traveling a far distance and even then it isn't at full throttle. Travelling in 3rd gear full throttle is hard on the undercarriage components. Wait, I forgot.......it is a rental. Have a ball :drinkup
I was using about half throttle, or a little more, when backing in 3rd which was a little faster than flat out in second and didn't seem to rattle the tracks much. Good vibration for compacting though. That is what got me to thinking about what would occur if something happened to the operator and it suddenly went full throttle. I don't particularly like going full throttle on any equipment. There is usually a sweet spot, torque wise, at somewhere around 2/3 throttle where everything works great. I did notice on this D6, that when when boiling dirt over itself on top of the blade, it liked full throttle or close to it. I talked to a seasoned dozer operator about this and his feelings were that the newer dozers operated better at full throttle than the older ones. I don't have enough experience on them to make a judgement.