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+--- Thread: Using a hydraulic gear pump to have a clutch (/showthread.php?tid=4277)
Using a hydraulic gear pump to have a clutch - svisara - 2022-10-08
Hey all, so I have a marine mounts setup for a raymarine rotary drive. Not wanting to spend $2k, but also not having space for a clumsy mechanical belt clutch, I was wondering about doing a hydraulic gear method.
This would give me a native clutch via the pump, and setup as though it were a linear actuator.
Can anyone help sanity check this - especially wrt strength/durability, and speed of pump translating into necessary speed of wheel? For example, I own an octopus pump that pumps 1 liter /minute which equates to .0044 gallons or ~1 cubic inch per second.
This hydraulic gear pump spins (I believe) at .6 cubic inches per revolution. So I could turn the shaft at ~1.7 rps (edit: rounds per second, not minute)? Do you think that is a workable speed?
Thanks for any input
example pump:
https://www.magisterhyd.com/product/0-50-cid-hydraulic-gear-pump-3-4inch-keyed-shaft-ccw/?gclid=CjwKCAjwv4SaBhBPEiwA9YzZvEOIR95EE5WfABSuxK5epuXEi_C4cPsR0wXvRye_3QqmmX9Oy4J6IRoCFJwQAvD_BwE
RE: Using a hydraulic gear pump to have a clutch - seandepagnier - 2022-10-08
I am not sure which shaft at 1.7rpm. If the rudder shaft, then ok. If it is the wheel, maybe not.
Normally -30 to 30 degrees of rudder takes 6-10 seconds.
RE: Using a hydraulic gear pump to have a clutch - svisara - 2022-10-09
Ah yes, this would be for the wheel
edit got my units wrong. 1.7 rounds per *second*
For me, I believe lock to lock is 2 revolutions of the wheel. So I'd need a slower gear pump or gear
RE: Using a hydraulic gear pump to have a clutch - svisara - 2022-10-10
Latest idea: a 1L/min (1 cubic inch/sec) octopus autopilot pump, a gear pump like this that rotates once per 1.42 cubic inches. Also, it's a bidirectional pump; most are unidirectional.
https://m.northerntool.com/shop/tools/product_200641997_200641997
...that theoretically would give me .70 rounds per second. On that gear pump, I can have a 10 tooth sprocket, with a 25 tooth on the wheel. That would give me a .28 rounds per second, or just over 7 seconds lock to lock. That's the plan! Let me know how this might fail!
RE: Using a hydraulic gear pump to have a clutch - seandepagnier - 2022-10-10
This seems right. It really depends on the boat. I have rigged my boat to do 2 seconds rather than the typical 6-8 but I am also sailing at speeds > 10 knots, but my rudder stalls beyond 20 degrees rather than 30, and I may have still overdone it.
RE: Using a hydraulic gear pump to have a clutch - svisara - 2022-10-11
Copy, well it may take a few months but I'll report back when I try it
RE: Using a hydraulic gear pump to have a clutch - kniven - 2022-10-11
(2022-10-10, 09:12 PM)seandepagnier Wrote: This seems right. It really depends on the boat. I have rigged my boat to do 2 seconds rather than the typical 6-8 but I am also sailing at speeds > 10 knots, but my rudder stalls beyond 20 degrees rather than 30, and I may have still overdone it.
Sean. How do you easily check the rudder end-to-end travel time? And which parameter determines the duration.
I have a slightly oversize hydraulic pump for my boat, with an adjustable flow rate. https://www.marinepanservice.com/en/accessorio/ls-rv2
Right now, the pump is adjusted near the minimum flow rate, and seems to be working happily (just did a Norway-Shetland passage in quite rough conditions, and the motor was working without any issues. The overall current draw for the autopilot system was ~5 A).
I assume there will be a "sweet spot" where the motor controller output amps and the pump flow rate has optimum efficiency in terms of current draw...
Maybe I should consider to adjust the flow rate somewhat up. I guess that would directly affect the rudder travel time.
Any thoughts?