August, if you post a pick i might know, if not, i know several ncco operators that will. I'm not an operator, I'm a steamfitter/ pipeliner, so a crane and an operator are simply tools i use to do my job. Not knocking their profession, i just tell them what i need and they push levers to do that. On most heavy picks that I've done, they are boomed way out past their vision, and are relying on relayed hand signals or radio communication to tell them what to do. Now knowing being around equipment long enough, if there is a right to left toggle button, that is usually an auxiliary hydraulic feed, for some implement. If you are referring to the spinning knob that moves with the load line, that is to help the operator "feel" the amount of line payout, so they can do the hardest thing an operator has to do, which is booming up or down while holding the load at a set height. That is the test to see who is a regular operator who does cranes vs a crane operator who runs other equipment. If they can also swing while performing that accurately they are in the .00001 percent. The best operator i have ever seen performed that exact manoeuver while i was walking back from the trailer, where the load travelled directly in my line of sight, and the load didn't swing left or right more than 2 feet either way, while booming down and raising the load line (holding the load), he didn't go up or down a foot while moving the load over 100 feet in about 2 seconds. Needless to say, he was a bad mofo.
Edit: VERY IMPORTANT: I'm sure you are aware, but be very careful about two blocking with a crane. If I'm not mistaken, the knob you are referring to is to show the winch line movement, which I've mentioned helps when holding a load. Obviously, when you boom up, the winch line if held still will raise the load, possibly until the load contacts the block on the end of the boom. If this happens, the leverage will easily separate the line, and horrible shit will happen. Doing tree work, i imagine you will be at capacity, reach, and height quite often. It is especially important to be anally cautious about this danger, to the point that taking forever is almost too fast. The consequences of 2 blocking are so severe that doing otherwise can be fatal or worse.
Edit 2: make sure, every day, that the 2 block safety is working correctly. With the boom down as low as possible, cable in until it shuts off, or it lifts the sensor and doesn't trip. If that's not working correctly, did not attempt to work, that is an immediate do not pass go moment. Cranes are awesome, but with that power comes immense respect or terrible shit happens. Also check level with a very nice 4 to 6 foot level, on the deck, in both directions. Don't trust the bubble in bubble thing. Every good operator I've ever met did this. Make sure to pick up our the wheels completely. Finally, do not skimp on cribbing under your outriggers. I watched a 30 ton go to the tipping point and set back down because an outrigger sank in the asphalt. Build some large area pads, and use them religiously. Working residentially, you will deal with unknown soil conditions, and once again it's too great to risk. These are some of the best tips I've learned over the years.
Edit whatever number I'm on: remember cranes load charts are for the exact capacity, not taking in to account shock load. Yes they have a safety built in, but it's quite unwise to push that. Kind of the one ton truck to pull a mower trailer vs a half ton to pull a gooseneck. Anything over 75 percent, aka with unknown weights that are cut free with potential shock load, are deemed critical picks. What that means is that you are pushing the crane to the point that both osha and the crane manufacturers have stated that's the point where you need to fully engineer a pick. At that point, shock looking can easily tip a crane, or overload it's components. I've talked about duty cycle loading before, and i probably should again, not because you need me to, but maybe someone might pick something up from it.
When you stress steel over and over again, in time it will harden and crack. A hydraulic crane is designed to bend over until it hits the gibs, which then stop that part from bending anymore, and the boom becomes a cantilever. Loading cycles slowly work harden the steel, bending it over and over again until it forms cracks and breaks. Steel, as do most materials, have plastic deformation and permanent deformation figures. When you are pushing to critical lift status, you are either approaching the tipping point, or are hitting the point where the boom, hydraulics, or winches will be overloaded to the point of damage. With the expense of the crane, extreme care needs to be taken to preserve it's integrity. In my opinion, far more so than another other form of machinery.
So crane manufactures have chosen a phrase for repetitive, fast as possible actions on a crane, it's called duty cycle work. If that sounds strikingly similar to tree work, that's because it's the same damn thing. Ironwork is picking relatively light weight beams in location, all day every day. Basically the exact same as tree work. Duty cycle work requires a lattice boom crane, which can handle the acceleration, shock loads, and rapid loading and unloading cycles. Afaik no hydraulic boom has ever been approved for duty cycle work. So please proceed with caution. Your incredible effort, and in my humble opinion, God's plan, has allowed you this incredible opportunity and tool, and i wish you the best my friend.