So what am I reading at the moment? Well, I just finished Moneyball by Michael Lewis. The subject of the book is American baseball. I'm not a baseball fan and know very little about the sport - although I now know more than I did. But that's not why I read it.

When it was first published, Moneyball created a big stir in baseball circles because it challenged the status quo. In the Afterword, the author remarks on the fact that some of the most ardent critics of his book from within baseball circles hadn't even bothered to read it. As someone who's written a book considered by many to be controversial, this is something I can definitely relate to.

Moneyball is about many things other than professional baseball. But the overarching ones is: be wary of the majority. Just because the majority does something a certain way, it doesn't mean it is correct - or the best or most efficient way of doing things.

I can tie this 'majority-is-wrong' principle to more than a few issues in hydraulics. One that comes to mind, and which won't be new to you unless you've recently joined this forum, is the use of pump suction strainers.

I'm not a fan of suction strainers and actively campaign against their use. But as the author of Moneyball found out, when you take a position against the majority, there will by many who disagree with you. And so I regularly hear from folk who feel they need to explain to me why their hydraulic system is different and why they have no alternative but to use this pump-killing device. This one is typical:

"I disagree with your position on suction strainers. On our machines we have up to 6 pumps fed from a manifold. All have suction strainers fitted. When a pump expires it sends metal everywhere as well as into the intake manifold. These strainers catch the big lumps and stop it being sucked into the next pump. So if these strainers were omitted in our situation it could get very costly as there'd be several pumps to replace instead of one."

There are a few possible exceptions to the rule of NOT using suction strainers, but this isn't one of them. This member didn't send me a diagram of the pump and manifold arrangement, but if suction strainers are necessary for the reasons he states, then it is only due to bad design: the manifold must be below the pumps' inlets. Think about it. If there is a head of oil above the manifold and the manifold is above the pumps' inlets, then for cross contamination to occur, debris has to travel uphill against a positive head of oil. Highly unlikely.

And, more importantly, if this machine did require suction strainers due to brain-dead dumb design, an informed machine owner would never buy it in the first place.

Anyway, I prefer not to argue with people who've convinced themselves of the merits of suction strainers - or as in the above case, use them as a substitute for proper design. I just refer them to pump manufacturers' recommendations. Just the other day I was flicking through an old Rexroth manual that dates back to 1979. Here's an excerpt of what it says about suction filters/strainers:

"The advantages of suction filtration are strongly outweighed by the disadvantage of the pressure drop created by the element… Any benefit the suction filter offers by keeping contamination out of the pump, is offset by the possibility of damaging the pump because of cavitation…"

"Another major disadvantage of the suction strainer is that it is located inside the oil reservoir which makes it inconvenient to service. It is for this reason many suction strainers in hydraulic systems go unserviced until they starve the pump and cause cavitation damage."

"Due to these disadvantages, a fine degree of filtration at the inlet of the pump is specifically not recommended (italics theirs not mine)."

It speaks volumes about the hydraulics industry, that this 30-year-old advice from a leading hydraulic pump manufacturer is still widely ignored today.

I wonder if Moneyball will have a more rapid influence on the way Big League baseball teams are managed? Maybe it already has.