These are notes that I am writing to help me learn our industrial history. They are my best understanding, but that does not mean they are a correct understanding.
Monday, July 11, 2016
Hydraulic Motors
I have already described hydraulic cylinders or linear actuators. Here I look at rotary actuators.
20140806 0236
Road graders needed to be able to push the blade down as well as lift it up. To do this double-action motion with cylinders requires a high-pressure seal around the ram. Until they invented those seals, rotary actuators were used. Below is a closeup of the hydraulic motor and crankshaft that operates the left side of the blade.
Zoomed in
Zoomed in
A hydraulic motor is used to adjust the angle of the blade by turning a pinion that is engaged with a circular rack on top of the blade.
Looking at how the ripper in front of the blade is raised and lowered, I see that this grader was built during the transition from motors to double-acting rams because it uses little rams instead of motors for light duty work.
Zoomed in
If you look at older graders, you will see that a rotary hydraulic actuator is used to control the height of the ripper as well as the blade.
In a 1937 Cat grader, everything was controlled by rotary motion. This picture details how a rack and pinion was used to move the blade from side to side.
Eventually, all motions in a road grader where done with rams. Unfortunately, the specs for that John Deere 570A grader do not indicate when it was built.
For decades, I quit seeing hydraulic motors on equipment. It might be because I was too busy earning a living and did not have time to look at industrial equipment. But now that I'm retired and looking at stuff again, I'm finding that hydraulic motors have been developed so that they can now handle a lot of power and/or speed.
In some designs, hydraulic motors are used to avoid the expense of using shafts, gears, and chains to deliver rotary motion such as in a rock picker.
When I noticed these hoses on the wheat header of a John Deere 9550 Combine, I wonder if they use a hydraulic motor to drive the reel so that it is easier to adjust the reel speed to be consistent with the ground speed. But I don't know why there are three hoses. The next time I visit a dealer with combines, I need to take a closer look at the wheat headers.
This video illustrates that a rather small motor can spin at high speed with quite a bit of torque.
The screenshot below is from a video that starts with some machines that use hydraulic motors to power a cutting implement at the end of a boom. But the screenshot highlights the 300 hp "Claas Octopus" for trimming drainage ditches. There are a couple more screen shots from the video.
Screenshot
The kid with the remote had been pushing the engine hard. This is just before he actually stalls the engine, twice. And it is not a small engine. I think the job might go faster if he took smaller slices and let the wheel keep rotating near top speed. It would take more slices, but the slices would go faster.
The engine mounted on the rear of the crane is powering the vibro-head of the pile driver. (Right-click the video so that you can get the URL and watch it in a separate window so that the full-screen option works.)
No comments:
Post a Comment