How to analyze power? hp vs breakout force vs ...

I’m in the market for a 10k/lb used mini ex that will be used primarily for digging stumps, pulling rock and land clearing.

In that 5 ton range I often look at hp, since I want the most power I can find. But a Cat 304 has 36hp vs a Bobcat 435 with 49hp - should I be looking at bucket digging force instead? I can’t always find breakout force but I see the 304 has a mean breakout force, but I would expect it to be underpowered with only has 36hp. Am I wrong?

What should I be analyzing to determine power when comparing options?

That's not what I'd be looking at buying used. If I was buying a fleet of them then maybe comparing PRODUCTIVITY would be worthwhile, but I bet that's rarely in the top three for a mini excavator. Get above 40 tons and the productivity will be number one or two.

I don't think I'd even bother looking at HP, would you rather have a pickup with a two speed transmission or a ten speed?

You better be looking at the product support for the different machines too. You could end up with a good machine that no one knows how to repair.

Delmer said:

That's not what I'd be looking at buying used. If I was buying a fleet of them then maybe comparing PRODUCTIVITY would be worthwhile, but I bet that's rarely in the top three for a mini excavator. Get above 40 tons and the productivity will be number one or two.

I don't think I'd even bother looking at HP, would you rather have a pickup with a two speed transmission or a ten speed?

Click to expand...

Mmm, not sure I understand your response. I’m not looking for a 40t fleet for productivity. I’m looking at the 5t class and am wondering how a 36hp 9k# cat 304 compares to 49hp 10k# in terms of stump clearing, rock picking up, land clearing. What impact does the little cat’s small hp footprint have compared to a 49hp Bobcat?

I didn't answer your questions very well, it was late.

The weight difference is not that significant, the HP difference it pretty big, but that's not the only factor in productivity. The efficiency of the hydraulic system comes into play, ergonomics, the design of the machine, leverage, size of the cylinders etc. Have you ever driven a truck with a two speed transmission? compared to even a four speed of the same era, you get a lot less work done with the HP available. Same with hydraulics, ever used a single stage log splitter? HP is not the biggest factor.

You're not even talking about productivity, you mention break out force, which is a decent measure of the "size" of an excavator, but then there's the factor of duty cycle. Mini excavators are LESS engineered than the big ones, easier to abuse to destruction. It's easy to make a machine that has lots of force, and then if you work at that maximum force it will fall apart in very few hours. If you instead work a lighter "force" machine to it's maximum level it may last many times the stronger one and work more economically as a result.

Your best answer is going to come from somebody who has operated both in similar conditions, not me. Or you could post some pics of the types of projects you intend to use it on to see if you're even in the right ballpark. I don't know what experience you have, just guessing based on the very little I've read in your posts.

Short answer, weight is most important to me, that weight is "weighted" based on the manufacturers reputation, hard to beat CAT, but ask somebody who's run them both or similar.

Other short answer, condition/price is the most important factor for anything I buy used. Unless you're locked into these as the biggest you can haul and plan to haul them often, widen your range if looking used.

One metric to consider is hydraulic flow rate when comparing machines, my Bobcat E42 (9500 pounds) has a flow rate of 20 gpm. You could compare specs between the E42 and the 435, my E42 does everything I ask it to do.

John Canfield said:

One metric to consider is hydraulic flow rate when comparing machines, my Bobcat E42 (9500 pounds) has a flow rate of 20 gpm. You could compare specs between the E42 and the 435, my E42 does everything I ask it to do.

Click to expand...

You bring up a good comparison. The e42 is right in the middle in terms of hp/weight in this class but has a pretty large breakout force. Then there are Komatsu's. Similar to the Cat 304, Komatsu's have small hp engines compared to their class. For example, a PC55 is almost 12k pounds but is only 38 hp, that's about 10hp less than others in that size class. That is a considerable % drop. I would expect them to be less powerful in some respects as a result. The PC55 does have a pretty low breakout force for that size - maybe that is the tradeoff. But then, the Cat 304 has a big breakout force with small hp. So, {shoulder shrug}.

I wouldn't get hung up on one parameter like HP, for me engine torque is a more useful indicator of its ability to do work.

John Canfield said:

I wouldn't get hung up on one parameter like HP, for me engine torque is a more useful indicator of its ability to do work.

Click to expand...

I wouldn't say I'm hung up on HP, but at some point there are diminishing returns. I suppose I'm trying to get a better sense of when a machine gets to be too underpowered for my needs.

HP really matters on excavators when trying to push higher GPM and PSI. So if your running attachments on a mini ex, hp can be important Thats why CAT mini ex's struggle with that. If your running at higher altitude, hp/turbo matters.....a lot. I live at 5k and work up to 10k, the power drop off is significant.

Bucket Breakout is important. I pull a lot of concrete and stumps and dig in hard frozen ground so breakout is important to me also. Remember that these numbers are typically pulled from the OEM with a bucket with a tight tip radius. So sometimes the breakout numbers can be made artificially high by using a bucket that you would never use in the real world, but makes great breakout numbers. Also certain quick couplers will reduce breakout. Things to be aware of.

Arm Breakout is also important. It seems some excavators are bucket diggers and some are arm diggers. Both have their advantages.

As far as what to make all of this. I think knowing what your looking to do with the machine helps set the stage. If your running a mower attachment or hoe pac or something like that, then hp numbers can be important. You live at a low alt. so that is not an issue.

If your digging stumps and bucket breakout type work is important, than look at the machines that are specing high breakout numbers, then test drive them and confirm what the paper says.

KSSS said:

HP really matters on excavators when trying to push higher GPM and PSI. So if your running attachments on a mini ex, hp can be important Thats why CAT mini ex's struggle with that. If your running at higher altitude, hp/turbo matters.....a lot. I live at 5k and work up to 10k, the power drop off is significant.

Bucket Breakout is important. I pull a lot of concrete and stumps and dig in hard frozen ground so breakout is important to me also. Remember that these numbers are typically pulled from the OEM with a bucket with a tight tip radius. So sometimes the breakout numbers can be made artificially high by using a bucket that you would never use in the real world, but makes great breakout numbers. Also certain quick couplers will reduce breakout. Things to be aware of.

Arm Breakout is also important. It seems some excavators are bucket diggers and some are arm diggers. Both have their advantages.

As far as what to make all of this. I think knowing what your looking to do with the machine helps set the stage. If your running a mower attachment or hoe pac or something like that, then hp numbers can be important. You live at a low alt. so that is not an issue.

If your digging stumps and bucket breakout type work is important, than look at the machines that are specing high breakout numbers, then test drive them and confirm what the paper says.

Click to expand...

This is great, thanks KSSS. I'm land clearing at low alt, picking up logs, digging stumps and rocks, so bucket/arm breakout are most important. HP doesn't have much influence there?

Another item that hasn't been mentioned that goes along with horsepower is the speed of operation. The high breakout force machines do that with smaller horsepower by the machine working slower. Maybe by the specs book you can pick out a stump or a concrete knob. But then again it takes all day to do it and even longer to move to where you want it to be. Horsepower gives you that speed of operation. I'd also look at the torque output on the engine as a better spec for figuring the ability of the machine. Cat and Komatsu use small engines and horsepower / torque to get fuel economy. More ponies, more feed.

No I don't believe it does in your case . The way the hyd system is engineered is also important, some such as CAT typically use one pump, others I have seen use up to four pumps. The ability to multifunction is important to most operators, something to look for when your demoing machines. If I were you, I would be most concerned about bucket breakout, then arm breakout and lastly hp. I would be sure to get a coupler, pulling stumps will like push you to change out bucket configuration often. I mostly agree with John's points, but I think how an OEM configures the hyd. system is really where the sausage is made. That is why demoing is important, some of those things can only be learned by demoing it, and running it like you expect to use it.

I think it all depends on the hyd. system. Older Bobcat machines had way more HP but used gear pumps that weren't nearly as efficient as piston pumps which are basically a load sensing system. Some machines operate a lot smoother too so trying out different machines is important. I ran a Nagano (Japanese) with piston pumps and pilot controls and it was way nicer to run than a Bobcat 331 but this quite a few years ago. I think Bobcat has made some improvements since then.

I would say it all depends on the adjustment of the maschine. For example a pc55, I can take two off the production line, when I get done with my adjusment, it will have more power and faster then the other. I compared it to our pc88 8ton class without any adjustments done and the pc55 had just as much power. So it all really depends on where you buy the maschine and if the tech knows what they are doing with the maschine, or what the maschine is capable of handling, then you shouldn't have a problem. A few considerations to look for, can I travel with my maschine when my maschine is on min. Idle and turn the maschine aswell low idle/On rabbit, or when I operate my maschine 2 or 3 functions at once on low idle does my maschine stall out, when then not properly adjusted by the stall tests. So just to take in for consideration

My experience with stump removal on a mini excavator (3500-13,000lb machines), is that it's easy to break the teeth off an old bucket, blow old and weak hydraulic hoses, and do damage to pins and bushings. Especially if you got the engine maxed out and your just tugging away. Regarding spec, I would look at bucket break out force. Moving the bucket will do the most to loosen a stump. Mostly you're just going to dig around the stump at 3/4 power, sawzall some root arms, and drag the stump out. Lifting capacity can be a big factor. You can get the stump out, but then you can't lift it into a dump truck even with barn doors or a highlift gate. As someone mentioned, good to have a local dealer near you. I'm a Takeuchi guy. The TB240 has similar spec to a lot of 5 ton machines, but is lighter to tow. Overall, I don't think the 5 ton machine is the size machine to remove stumps bigger than three foot in dia, and is much better for two feet in dia and smaller.

I was trying to dig out a recently cut double trunk live oak, each trunk was maybe 30 inches but joined near grade level. Our oaks have a shallow root system (no tap root) but they spread out for 15 or 20 plus feet. I worked on that double trunk for three or four hours, my contractor buddy tried for another hour or two. We finally got a stump grinder guy out that worked on any root he could access, fortunately his machine could extend out to reach the root mass or that idea would have been a bust. Finally we broke it loose thanks to several large cut roots. It's not a huge problem digging out 24-30 inch tree stumps as Peter mentioned.

One of the big advantages of the TB/FR series of Taki excavators is their ability to lift. Where a typical swing boom machine rotates out in front of the cab the FR rotates more to the center of the machine. This leverage advantage makes a big difference in lift capacity. It is not without some disadvantages, a lot of grease zerks and a lot going on mechanically to make that happen but they do things that nothing else can. My biggest feat with it was pulling out a partially rotted stump that measured 13' across. No easy task loading on a flat bed and moving down the road wasnt easy either but the machine did it.

I too have the TB153FR. I managed to remove these two stumps. Took a long time. Very hard to loosen and drag out. I could not lift them, had to just push them and leave them. Not sure what the property owner did with them, maybe burned them. One of the main bushings fell out of the stick. A small bar holds the bushing from slipping down and one of the bolts was loose. We managed to get the bushing back in, a lucky feat, and I made a new bar that fit into the slot better. I'm done with big stump removal in a mini excavator.

Here is the stump and another one removed