I want to learn as much as I can about marine propellors. I want to start with the maths side first and although all the basics are covered in general maths educational materials, I am looking for something more biased towards marine propulsion. Does anyone know a website with lots of diagrams...
Probably a very simple question but I can't find an answer. For current controlled proportional solenoids such as those used on hydraulic directional control valves, why is a PWM signal needed? Why can't I use a variable resistor in series?
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This is a 26mm o-ring which failed after not much use. It was being exposed to 200 Bar every 30 seconds, 8 hours a day for a few days before failing.
I have two questions.
1. How is this sort of o-ring made? It looks like it has been rolled from a flat sheet but I...
After much Googling, I can't find a solid answer anywhere.
What is the accepted pressure on the suction side of an axial piston pump? There are plenty of charts out there with velocity ranges suggested but no real useful information regarding actual pressure.
Looking through pump catalogues...
I am not an electrical engineer so I am not familiar with these motors at all.
It is a single phase 240V AC motor. Rated 2.2KW. It has a 16A power feed with a 16A fuse but when the motor is loaded up, the fuse blows.
240V, 16A = ~3.8KW
How is it possible for the motor to draw over 2.2KW or is...
Hi guys,
I have a problem whereby a rotary actuator will overspeed on startup causing issues. It has a flow control valve before it that can't handle the sudden influx of flow and will send 10-50% more oil to the actuator in the initial 2-3 seconds. This is a load sensing system with the LS...
General opinion on this guy? I get his emails with basic tips and tricks which have been useful as a relative newbie to hydraulics.
His book for sale is forced down any readers throat which automatically rings alarm bells. His website, whilst it contains a little bit of useful information is...
Hi guys, got what is probably a simple question for you.
Radial piston motors
Closed loop drive system.
Hydraulic brakes
PM is an electric motor which is on/off as you use the machine.
The issue as you can imagine is when driven up a slope and the motor is stopped, the radial piston motors...
Variable displacement on a large diesel engine.
How to simulate loading? Hand pump directly on LS and a PRV on the outlet of the pump going back to tank?
Hi guys, another question for you.
4 wheel drive mobile machine.
Main pump is a gear pump
Electro proportional spool control
4 axial piston motors. (2 motors on each side hosed in series).
Please note, there is no flow divider, just the drive spool direct to the wheel motors with a cross line...
I am in need of marine proof outboard gearboxes, capable of handling ~60nm with a gear ratio of between 4 and 5:1.
Ideally need to be able to purchase a sample first but large availability must be there.
I tried in the transmission forum but figured someone here might know of a place. UK...
Does anyone know of individual units that can be bought for trial purposes other than those on the bottom of most outboard engines which seem to have a reduction ratio more like 2:1
Thanks
I have a PWM solenoid driver test board. Basically a little board which I feed 12v, hook up to a solenoid and a 3 pin pot. I have 2 of these working in conjunction for a bi directional test box I use. Each board has 2 adjustment screws. One if for the minimum bias and the other is the range.
I...
I have an Excel sheet for various calculations with cylinder volume and flow calculators and HP and Torque calcs for engine power etc.
I am looking for one with 3 entries. Flow, Pressure and restrictor size. I saw one with 3 columns. Each column you would be able to change 2 of the inputs to...
Hi guys, quick one for you (potentially)
Mobile machine, driven almost entirely by hydraulics. Very slow so I take some readings.
Main pressure is 15 bar at idle when it should be ~25bar, LS is 4 bar. The Delta P stays around 10-11 bar right up to maximum pressure of 280 bar. Delta P should...
After reading this thread I have been wondering about turbulent and laminar flow in hydraulics and whether a similar principle applies.
The basic idea is that if after a certain component in a system, there is turbulent flow, whether or not a 90 degree elbow will help cure this. I am no expert...
Hi everyone,
Lets say you have a small hydraulic motor spinning at 1500rpm at 8l/min with no restriction. Then I introduce a 1.3mm restriction on one side and it makes no difference, but if I add another on the other side it slows to 1200rpm. Can someone explain how another restrictor of the...
Hi everyone.
I have a question for you. Do any big manufacturers of machinery use gravity to lower hydraulic booms? Obviously most are powered down using counterbalance valves which uses energy and in this day and age, efficiency is more important than ever.
I can't find anything online but...
