Running a low flow brush cutter on a high flow machine

[Skidud]

I cranked the relief valve down to increase it to 3,000 psi. It has made a HUGE difference. The mower was virtually unusable at 2300 psi. It would stall on everything it hit. That was a few years and a couple hundred hours of mower operation ago. I've not seen any ill side affects "so far." YMMV. If I could just get it spinning quicker, I'd have a great setup for what I use it for.

 

[Skidud]

I've pretty much resigned to the fact that I am going to have to pin it and go or find a higher flowing XT series.

 

[Welder Dave]

If you have enough flow higher pressure will give you more more torque/ power than increasing the flow. If you only had 2000 PSI you could have 50 GPM but your motor would just stall. 25 GPM at 3000 PSI would be much more effective. Flow x pressure is deceiving. Kind of like the ridiculous air compressor ratings. A 6.5 HP motor will not run on 120 volts.

 

[phil314]

That can't quite be right, according to Willie's specs posted there would be 36,800 hp. Is there a formula for that?

Formula is:
GPM x PSI / 1714 = HHP

1845c:
16 x 2300 /1714 = 21.47 hp

 

[phil314]

If you have enough flow higher pressure will give you more more torque/ power than increasing the flow. If you only had 2000 PSI you could have 50 GPM but your motor would just stall. 25 GPM at 3000 PSI would be much more effective.

This is only true if you have the wrong size motor on the brush cutter for the skid steers flow AND psi.
It's much like gearing. You can always trade flow & psi for any speed or torque you want.
You do that by changing the size of the motor. Same thing applies to snowblower. Has to match the machine.
Problam is the 1845c doesn't have great flow or psi. So you will never get an attachment that needs a lot of Hyd hp to work well. It will always be a compromise.

Flow x pressure is deceiving.

This is very true. But it you understand electricity, it's exactly the same.

 

[KSSS]

The 1845C was designed way before the attachment craze hit. Flow and PSI were not a big concern, as evident by the 56 hp. The XT series was designed as an attachment carrier offering an optional 5K psi high flow system on the 90-95XT.

 

[willie59]

The 1845C was designed way before the attachment craze hit. Flow and PSI were not a big concern, as evident by the 56 hp. The XT series was designed as an attachment carrier offering an optional 5K psi high flow system on the 90-95XT.

Nailed it!

 

[Welder Dave]

If you need a certain flow or pressure, increasing the other to compensate isn't a work around.