I'm hoping someone can tell me how much power I can take off of the accessory drive of a 3406 Cat engine. I'm thinking of adding an additional small hydraulic pump to the drive opening in the timing cover on the left side of the engine. This engine already has one hyd pump installed on the back side of the timing cover, and I'd like to add another to the front side of the cover. The mounting flanges and splined couplings are present on both sides of the drive gear. I can easily bolt this extra pump on, but I'm worried about overloading the drive gears on the front of the engine. If anyone could tell me the max continuous torque and max intermittent torque allowed it would be greatly appreciated. The existing pump requires approx 40 hp at full engine rpm (but is loaded intermittently) and the extra pump would require about 23 hp continuously. Am I asking for timing gear destruction? Many thanks, Marv
The front gear group can take in total about 70-80 HP. The fact that you are going to be running only 23 continuously but 63 intermittently should be fine. However it will shorten the life of the bearings in the front gear group so you should plan to keep an eye on them (overhaul) on a more frequent basis than you are doing now. Also if you're not doing oil analysis I suggest you start doing so before you do the modification and keep a particular eye on what the iron does before and after the mod.
Thanks Nigel. I had a hunch you would know the answer to this. Have a great weekend! Marv
I would love to be able to post something to definitively prove it, but the numbers are simply just not published by Cat, and to try to get them to allocate time & resources to do the necessary digging to find the original calculations as proof positive is a simply a waste of effort in this day & age where the use of every resource has to have a financial justification instead of simply satisfying someone's curiosity, or confirming a hunch. FYI on a lot of engine applications the air compressor is run off the location where you're planning to hang your hydraulic pump. I would reiterate my recommendation that you need to build up an oil analysis history of what the iron in the engine is doing BEFORE you make the change, then afterwards you can see what (if any) is the increase in wear directly attributable to the additional load. You may well be able to control things simply by shortening the oil change interval a tad, maybe by 10% or less.