9/9 how do you fill the closed loop system with oil without tank, thats what i missed the most :(

Brian Gillis Baie has

13/13 I would like to reiterate the fact that THERE IS NO HEAVY TECHNICAL VOCABULARY! It is refreshing to watch an engineering video that is straightforward and visually aiding.

@@martynasvizbaras1180 basically everything is built into the closed loop system . enough room for oil and the control valves. seems like the open system is more user friendly. easier to repair.

Well stated👍

I don't think it is the best simple practical explanation but it's not bad for a beginner.

@Ask APT No, moved out of the field 21 years ago. Still very passionate about all hydraulic. While mechanically I would imagine the systems remained similar, I am sure on the control side, there have been good developments over the past 20 years. All the best.

I also taught hyd and some folks just never really unstand how it works 😊 No matter how you explain it to them 😢 I loved working but had to retire at 68

Fantastic explanation,even a layman can understand ❤

But here is a flaw concerning the open loop system. Directional control valves are usually proportional. You can control the speed with the lever pretty well. You don't normally need any flow control valve that increases unneccessary pressure, energy consumption, heating and wear on the pump. On every tractor, loader, excavator etc with a fixed displacement pump for the working functions you control the hydraulic cylinders and even motors by the levers on the control valve and rarely any flow control valve is used. Controlling the speed of a cylinder is pretty much like controlling the speed of a motor.

@@ontheroadagain4773 Exactly. In most cases, you don't need a flow valve when you have a control valve that will do the same. The systems with solenoid control valves you do if you don't want full flow on part of the circuit.

Why are they not used in cars: Is there torque multiplication, Can they be used for high speed?

Wait why not use a closed loop since then you just have a pump on every ram instead of one with a complicated valve system?

@@braddavis4377Automatic cars have a torque converter, comparable to this closed loop with a fixed swash plate angle. Pumping fluid creates drag so its really only good for high torque low speed

On a car, the open loop system is the better choice for a lot of reasons! The variable speed ability is taken over by the engine, and gives you the ability to use sliding vane or gerotor pumps for simplicity and longevity. An example is a power-steering assembly. These systems pump fluid through an a little hole (called an orifice). At low engine speed, the orifice is too big to be a restriction, and the car is likely parked or has low duty requirements, so drag isn't a problem. You can turn your power steering pump with your hand! Pressure gain has exponential characteristics. Doubling engine speed will quadruple the pressure, and the engine often goes over 10-times the idle speed. Any shock loads against these systems are typically resolved with the tremendous amounts of momentum in the engine. For an Electric motor that rotates at a fixed frequency (60hz, geared down to whatever suits your nominal shaft torque requirements and pump speeds), the closed loop system makes sense, but has its own sacrifices. For example, we might need a sudden burst of speed. The motor often can't cope with this, or becomes a reactive load for the power source. The work-around is to have a huge flywheel on the motor. If you're dealing with shock loading, the flywheel will give you all of the load you could ever want, but the shock loads can trigger your safety valves, causing the system to go backwards.

Automatic transmissions have open-loop systems that are optimized for the duty at hand. You have control over engine speed and should be mature enough to know what kind of gear shifting duty the transmission would ever need to do. Given that information, an open loop system can be made, such that its mode of failure is known and forced to happen for safety reasons.

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But here is a flaw concerning the open loop system. Directional control valves are usually proportional. You can control the speed with the lever pretty well. You don't normally need any flow control valve that increases unneccessary pressure, energy consumption, heating and wear on the pump. On every tractor, loader, excavator etc with a fixed displacement pump for the working functions you control the hydraulic cylinders and even motors by the levers on the control valve and rarely any flow control valve is used. Controlling the speed of a cylinder is pretty much like controlling the speed of a motor.