Originally Posted by Espeefan
I would guess that like most things in life, there are always exceptions. Since the hydraulic pumps are coupled to the engine, it's not uncommon for the pump RPM to vary all the time too. Look at a wheel loader, for example. Lots of driving forward and backing up. In between, steering when the engine is winding down, or at idle, and lifting or dumping the bucket. Pump (oil flow) output varies quite a bit. Now something like a back-hoe or an excavator is a totally different story. Maybe even a skid-steer, but the demand for hydraulic flow on a machine that is constantly moving, and uses hydraulic motors for the drivetrain also, actually needs good flow, and maximium pump output. Then we also could consider the variable displacement hydraulic pumps, that put out more flow, when it is demanded, regardless of engine RPM.
So I would think on a small scale model there is no reason why the pump can't be throttled back to reduce heat, and increase battery life. Sounds like a win win situation to me. Heat is the worst enemy for a hydraulic system, next to oil contamination. Yes, you could put a heat exchanger on any hydraulic system, but on a scale model, it would be easier and cheaper to throttle back the pump, or shut it off completely.
Out in industry, where I work, we are starting to see some hydraulic pumps run with electric motors, and variable frequency motor drives, which throttle the motor and pump RPM back, when the flow is not needed. The worst is when an operator walks away from a machine and leaves it running. The oil is constantly going over the relief valve and the motor is drawing more power in doing so, while also heating up the oil for the next few hours. Yes, the heat exchangers cool the oil too, but it is still getting warmer then it normally would, if the machine is cycling.
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