“Chinese” electric chainsaws and delimbers: what are they worth?

[NCSH]

The performance of a hydraulic device depends on its application: at low speed and in linear movement, it is interesting, in rapid rotation it is very mediocre, but is justified in certain assemblies for the flexibility that it allows. Brief, a matter of compromise depending on the objectives. When possible, hydraulics used for regulation and classic mechanics for the power part constitute a good combination..
If the tire is even less good in terms of performance, it also has advantages, mainly ease of installation and maintenance and safety (in terms of possible leaks).

The overall efficiency of a hydraulic circuit: pump + motor(s) is between 70 and 80%... it's not "very" mediocre (otherwise you would think that monstrous heat sinks would be needed on the hydraulic motors of a few dozen hp...this is not the case even if there are radiators on the hydraulic circuits to obviously dissipate the 20 to 30%....) ...

Obviously this would probably be better (+ 10% to 15% approximately) with brushless direct coupling! What is “the genius” Musk waiting for to get started?

After the performance of the caterpillar is very crappy, we tried to estimate it: new-transport/power-of-a-mechanical-track-track-track-vs-wheels-t16197.html

But it's not its main function to move forward...

This solution has become essential for many construction vehicles, railcar trains, trucks, after various rants about American cars from the 50s...

In the end, we have a hydraulic clutch associated with a gearbox or a purely hydraulic transmission.

[Christophe]

Exactly and many cars use the brilliant torque converter system...which is nothing other than a compacted hydraulic pump-motor...if the efficiency was so poor it would not be used in automobiles.. .

In this regard, I came across a Chrysler advert which presented this system...in the 40s!!

I thought it was a much more recent thing (like the 70s or 80s)...

[Christophe]

Here it is...

ad chrysler torque converter.jpg (124.02 KB) Viewed 646 times

[NCSH]

Exactly and many cars use the brilliant torque converter system...which is nothing other than a compacted hydraulic pump-motor...if the efficiency was so poor it would not be used in automobiles.. .

In this regard, I came across a Chrysler advert which presented this system...in the 40s!!

I thought it was a much more recent thing (like the 70s or 80s)...

We must remain wary of all these hydraulic transmissions for cars, their performance if they had to be used permanently was often deplorable...
Indeed, it started in the 40s, European engine manufacturers did not focus much on it.
Only the "hydraulic clutches" associated with a gearbox guaranteed correct performance, close to that of the thermal engine: most of the time, the engine remained in gear (almost 100% of torque is transmitted), except when starting.

[Christophe]

A torque converter is used all the time...right?

Obviously there are more losses than a coupled mechanical clutch (10 hp maximum power?) but the absence of a cooler indicates that the efficiency is rather very good!

Ub why are we talking about this in my chainsaw topic again?

[NCSH]

The performance of a hydraulic device depends on its application: at low speed and in linear movement, it is interesting, in rapid rotation it is very mediocre, but is justified in certain assemblies for the flexibility that it allows. In short, a matter of compromise depending on the objectives. When possible, hydraulics used for regulation and classic mechanics for the power part constitute a good combination.
If the tire is even less good in terms of performance, it also has advantages, mainly ease of installation and maintenance and safety (in terms of possible leaks).

The overall efficiency of a hydraulic circuit: pump + motor(s) is between 70 and 80%...it's not "very" mediocre(otherwise you think that monstrous heat sinks would be needed on hydraulic motors of a few dozen hp...this is not the case even if there are radiators on the hydraulic circuits to obviously dissipate the 20 to 30% ....) ...

Obviously this would probably be better (+ 10% to 15% approximately) with brushless direct coupling! What is “the genius” Musk waiting for to get started?

After the performance of the caterpillar is very crappy, we tried to estimate it: new-transport/power-of-a-mechanical-track-track-track-vs-wheels-t16197.html

But it's not its main function to move forward...

70 to 80% pump+motor conversion efficiency, even if it assumes 90*90 to reach 81%...
It's pretty bad.
Only on machines of several tens of kW, or even hundreds.

It was Macro who launched this, big machines that make you dream...
And for which the electric batteries will be difficult to match: 16 hours of work per day in the middle of the forest.
This is why there are also non-fossil synthetic diesel projects, at a timescale which has not yet been specified.

[Christophe]

It's these orders of magnitude of power on these machines...

One solution does not preclude the other.

In short, can we refocus on the subject please? THANKS...

[Macro]

A torque converter is used all the time...right?

but the absence of a cooler indicates that the performance is rather very good!

All automatic transmissions have oil coolers in general these are water-oil exchangers, but also large flat aluminum casings with fins below the car... Hydraulic machines also oil radiators with forced air. ..

[Remundo]

Exactly and many cars use the brilliant torque converter system...which is nothing other than a compacted hydraulic pump-motor...if the efficiency was so poor it would not be used in automobiles.. .

In this regard, I came across a Chrysler advert which presented this system...in the 40s!!

I thought it was a much more recent thing (like the 70s or 80s)...

there are hydraulics and hydraulics.

Hydraulic pump motors have good efficiency (80-90%), on the other hand torque converters which laminate the oil, it is mediocre, it can even go to 0% when the transmitted torque is lower than the torque necessary to “tear off” the vehicle.

[Christophe]

Any motor that works in a vacuum also has zero efficiency...so what?

A torque converter cannot achieve 100% efficiency. In its classic three-piece design, the efficiency curve has the following form: zero efficiency at neutral, continued growth during the acceleration phase and efficiency which falls at cruise speed (coupling phase between the rotor and the turbine stator). The drop in efficiency at cruising speed comes from the turbulence generated by the immobility of the turbine body which, as said above, is today generally relaxed by freewheeling this casing using a detent.

Too bad there’s no curve…

ps: Macro there is no radiator on the torque converter...and the gearbox fins are ridiculously small....I don't know if it uses the same oil as the gearbox...

the wiki page is well done: https://fr.m.wikipedia.org/wiki/Convertisseur_de_couple I will read in detail on occasion