hydraulic fan motors...wtf?

[pishta]

OK, My SC400 has a hydraulic fan motor, I just shook my head thinking what an over-engineered car this was back in 93 but I guess this isnt that new. My question is Why TF? Is Electric not good enough? #-o

 

[TrailBeast]

Lexus and Toyota both used hydraulics on fans.
Supposed to be quieter and more powerful than electric, as well as being able to vary the speed instead of just on or off.

 

[Killer6]

Probably saves them money,lol. I have seen a couple of newer brand X vehicles
in the dealership recently w/them. I find it disturbing that they think its OK for electricity
to control the throttle and steering instead of me,but it's not up to spinning a fan in the
same conditions.I'm sure in a truck/SUV app. where water,mud and such may get at the
fan assy. (if you're actually using them off-road in those conditions), the hyd. system may
prove more reliable.
Other than taking some load off of the ever increasingly loaded electrical systems,
you know,everybody has to have 5 DVD players and screens for every spoiled rugrat etc.
money and operating cond. are the only reasons i can think of.
Variable electric fans have been around for decades,and fan noise is pretty much
controlled by blade design,the motor itself is silent really.

 

[charger426]

My RAM SRT-10 and all Gen 3 Vipers have them. The story goes they had some extra money for development after Dodge was bought by Benz. So they spent it on a hydraulic fan assembly. It's free HP really. They are taking fluid from the PS pump tagg is already pumping and has extra pressure that's not in use so why not use it to spin a fan. After my truck sits for a while it sounds like a jet spooling up as the lines in the fan fill up. Biggest problem I see happening is if I ever have a PS leak or cut a line I'm not steering and I'm over heating.

 

[67Dart273]

It may be more efficient, I don't know. What it is "NOT" is "free HP." It takes real power to move water and air. Alternators are not very efficient really I think the older ones barely cracked 50 - 60% which is way below some electric motors. Of course if you produce power off a belt,and lose power in that conversion, you lose even MORE power when you convert back to mechanical force........with a motor. I'd bet the overall conversion for an electric fan is only about 40%

I have no idea what a hydraulic pump runs in that regard. Since it must produce enough to run "in bypass" it can't be very high.

Kinda makes ya wonder why they don't just .....................BELT DRIVE the thing (fan)?

 

[AJ/FormS]

Belt drive cooling fans rule!

 

[PhillH]

Yep our GMC Envoy had one, imagine my suprise when I heard the price to order a new fan clutch.

 

[68cuda408]

they've been used in commercial vehicles for decades. especially rear engine designs with the radiators side mounted. no belts needed one hydro pump (usually the p/s pump) with a remote shared reservoir. And a flow controller to control fan speeds and maintain constant temps.

 

[TylerW]

You can't just put a belt on it in every case. FWD Camry's used those with a transverse engine.