Hello, According to ritchi specs, the 307C only has 64 l/min oil flow, compared to the Kubota kx080-3 at 144 l/min, and the Takeuchi tb175 at 138l/min: can anyone confirm this? That's a serious difference in performance, and I wonder what limitations it might put on the 307, compared with its rivals? Does it have enough flow to power a hammer, for instance? I've always quite fancied a 307c (offset boom), but this apparent lack of oil flow is quite concerning. Can anyone advise? Thanks
You have to compare apples to apples so make sure the horsepower and machine weight specs match each other as close as possible when you start comparing pump flows. First item that comes to mind is that auxiliary pump flow is what would be used to run a hammer and the Cat runs 16 gallons per minute, Taki runs 18 gallons per minute and the Kubota is 17 gallons per minute. All three machines are just over 18,000 pounds. Horse power for the Cat is 54, Taki 60 and Kubota at 66. Running a hammer is usually a single function action meaning that when you are beating on something you aren't swinging, traveling booming up or arming out so all are comparable to most any hammer in that weight range. Maybe the Cat can do the same work because they think their hydraulic system is that much more efficient and they don't need to burn the extra fuel. The other consideration comes with the actual use of that extra pump flow. Most all the manufacturers fudge those numbers to their advantage. In my experience using a flow meter on plenty of new and used machines I've found that actual flows to be different between advertised figures and even way different between the same model of machine. Finding 10% difference between two brand new machines is not hard to do. That is part of what gripes a lot of experienced operators when they jump between machines. What I'm saying is don't get wrapped up in specs to the exclusion of a machine that might work perfectly well. If you have a certain model of hammer check with that manufacture for an opinion. They will know who's machine will run it the best.
Pump flows as stated are always theoretical, and are usually not at rated pressure. At best new pumps are around 95% efficient and it doesn't take much wear or even manufacturing tolerances to lose another 5%, so without even trying you can lose one tenth of your flow. The charts are also varied around pressure and speed so there are situations where the real is much lower than than the theory.
Thanks for your comments John.
Thanks. Yes l can appreciate that, it's just the figures are so very different, and normally, in most respects, specs for the same machine weight class don't vary to such a degree.
The Tak and the Kubota are both near a ton heavier and have ten more horsepower than a standard 307C, and of course you made me google all three to actually check the specs... if you look for the fine print in the CAT brochure you will find that the flow spec is 64L x2 so total work flow is around 128 lpm? Sounds right to me for a machine with 54 hp, apologies for being lazy earlier. Brochure: http://s7d2.scene7.com/is/content/Caterpillar/C359045
Ah well, if that's the case, it would make a lot more sense. Thanks.
It was a valid question, as you say a huge difference in flow, and there had to be a reason for it. I unconsciously avoid Ritchie specs because they're rather generic. Seems like in this case they misled you I guess.