|Ben Stalvey posted|
I believe the components labelled drives are clutches. That is why these pre-hydraulic designs are called "friction drives." Clutches are plates of metal that are shoved against each other so that the friction between the powered plates cause the driven plates to turn. The levers in cranes since the days of steam power control the spacing between the clutch plates.
I drove enough tractors on my Grandfather's farm as a kid that I could drive stick-shift cars. This got me a high school job as an attendant in a parking lot where only the attendant's parked the cars because the parking spaces were so tight. I learned that with a clutch you can control the speed of the wheels. With an automatic transmission with a torque converter, you are controlling the torque, not the speed, of the wheels. You do not notice a difference between controlling speed vs. torque until you are on a slippery surface because of ice and/or snow. It is a lot easier starting the car if you can maintain a steady, slow speed. With an automatic transmission, the wheels would go from not turning to spinning in place once the torque overcame the starting friction. (BTW, controlling speed instead of torque is why locomotives switched from DC (torque) to AC (speed) as soon as the electronics where developed to handle lots of horsepower.)
(Update: A "DropBox" of drive diagrams from a William Platou posting.)
This is a Liebherr crawler I watched work this past Summer and Fall. Unfortunately, the owner, Creative Crane & Rigging, painted over the model number. But their web site indicates they own just one crawler --- 150 ton.
On the left is the winch for the boom. In the housing are two winches for hoist cables. On the boom is a third hoist winch that is not being used for this job, but it gives us an excellent view of the hydraulic motor that drives the hoist winch.
|At camera resolution|
The village allowed the crane company to close Main Street through downtown between midnight and 7:00am one Sunday morning. That is why this Oct 1, 2017, 5:46am shot of loading a crawler on a truck trailer has weird lighting. The combination of the max ISO on my camera, 6400, and the street lights allows us to see the hydraulic drive on the right, including the hoses that go through the frame to the crane's housing.
Below, the crane has just loaded the counterweight on the truck in front of the crane. The truck driver is moving the front pad in so that the highway width of the crane is reduced. The crane operator is done moving the rear pad in, and he is headed to the control box.
I barely caught the front outrigger moving into the truck. The truck driver is helping pick up and store the pads.