I was craning a big industrial oven (all bricks already removed) with my RT-60S and I felt, with the seat of my pants, that it was a significant load. What I noticed is that when I was swinging the cab, I felt like it was growling, maybe slightly vibrating or shaking as it was swung about. Is there something that should worry me? How do I check soundness of the swing bearing/turntable to make sure that I am safe?
Block the boom and put all the pressure you can on those blocks. Measure the distance from the frame to the top of the swing bearing. Pick the boom up and make a lift near capacity. I thing it's supposed to be under .5" right at the swing bearing. Don't hold me to that number. I'd pump about 3/4 tubes of grease into the swing bearing. Have someone swinging the crane while your greasing. And don't use the cheapest grease you can find.
I was taught to use a dial indicator to measure turntable bearing runout. Scope out 50'-60' of boom, then boom down pretty flat (you shouldn't need a load) with the crane leveled up on jacks. Measure the distance between a flat point on the deck, and a flat point on the upper. Do that on the back/ counterweight side, opposite the boom base pins. Then scope all the boom back in, then go to max boom angle and measure it again. You've used the boom weight to rock the bearing each way. You can also tell if you boom to max angle, then bump the boom lever a little back and forth. If the turntable bearing is shot, the house will really rock back and forth. You don't have to get real wild with the lever to feel it. This is how I usually check one when looking at one to buy. You can have a lot of rock and still be within factory specs. I was in a Grove with a loose one for a while and it still measured good, you just really noticed it booming up and down. I know you're running with no scale. I'll make a plug for Cranesmart scales. One 12v wire and your up and running. I realize their like $4,000, but I won't let anyone leave the shop (I'm in the rental game) anymore with no scale. I would do this when I didn't have a scale. On that oven your picking, I would measure out my radius, then look at my chart. If I was only good for 20,000lbs, I would put in 4 parts of line in one of our 25 ton cranes. I know that its winch starts to protest once it gets around 5,000lbs per part of line. Then if you winch up till the winch would protest, and its not off the ground, I knew I was out of chart. If I was good for 15,000lbs, I'd put in a 3 part. If I was only good for 10,000lbs, I'd only use a 2 part. Once you know about what your winch will line pull, before it stalls out or you have to rev the engine way up, you can use your winch as a crude scale. If your winch will pull 6,000 or 7000lbs, then just use that for your multiplier. To figure out what your winch will pick, pick up some known weight (like your semi trailer, or one of your forklifts) with different parts of line. Don't just pop in 8 parts of line and keep cabling up. somethings gonna give. It is more accurate than waiting for a outrigger to lift. Plus where your loading heavy stuff up close, your not in your tipping chart, your in the structural portion of the chart. Meaning your going to break something before you tip. Its really the only way I know to lift unknown weights, without a scale, when your in the structural portion of the chart. I have one crane that growls pretty good under a heavy load, if your really pushing that crane, its going to let you know. Some of my other ones are nice and smooth, but most smaller cranes at a max pick you will have to throttle up to get them to swing around.
Thank you knepptune. Do you know where the lubricating fittings might be?
Crape operator, thank you very much. I will do along the lines of what you and knepptune suggest and measure how that distance changes with and without a load (fully extended and lowered boom will work pretty good I think). As far as what I do to prevent tip-over, is mostly common sense since the weight on many things, like that oven, is not known. For anything of non-trivial weight: If I need to take it out of somewhere, what I do is try to lift it, then immediately boom in and reduce the radius, that way I know that if I picked it, and boomed it, I am not in danger. If I have to put it out to somewhere, I measure the radius and boom out near the ground with the load at least out to that radius, if all is OK then I proceed with lifting. I am a machinery mover and scrapper and most of the time, I need the crane to take things out of something and put them down, not as dangerous as putting them up and out. I do not really do construction and such where it is the opposite. I also have a crane scale, which I have not yet had the chance to use but I have it. Also, forgot to say, I acquired four sets of plywood outrigger pads. One set is huge 4x4ft pads, and another set is smaller 2x2 feet pads. Just last week, I was lifting with the crane on a lawn (soft ground) and used those 4x4ft pads and 2x2 pads on top of them, it was very nice. I doubt that 2x2 pads would have sufficed.
I'm not sure where they are on that particular model. Usually you'll find two grease zerts mounted to a plate with lines going to swing bearing. Most every grove I've ever seen had that set up. I'd check on the side of the upper opposite the cab. If you've never greased the swing I'll about bet that it just needs grease. I'll second crane op on the load cell. Definitely worth their weight. When I used to run a crane with out a scale I used to take the load out as far as I could directly over the side. Directly over the side is usually the weakest part of the chart. On that rt60s over the front is your best chart so if you take it out over the side and your good you should be good to set it over the front. Don't take something out over the front then set it over the side. Could get yourself in trouble there.