| Author | Message | ||
| Jim and Myrna Lawrence (Daffycanuck)
Rating: N/A |
I need to know what the 'general' flow and pressure requirements are for the power steering boxes that are installed in our busses.....I know they are all different, but in general...? What would the effect be of installing a pump with a larger flow and pressure. | ||
| jimmci9 #2 Rating: N/A |
without looking at specs, i cant remember the the volume, but max pressure is around 2500 psi.... installing a larger volume/higher pressure pump is not a good idea, as it will overheat the system as pressure lost to a relief valve equals heat....do you have a power steering problwm or are you planning on using the power steering hydraulics for anote purpose, like a hydraulic fan???.... ive got several used (but good) vickers power steering pumps.... some direct mount on the back of a detroit, others are pulley driven... jimcat2@webtv.net if interested | ||
| Marc Bourget Rating: N/A |
Off the test bench for the PS pumps I used to rebuild there is an inverse ratio to volume and pressure, high pressure at low flow or low pressure at high volume of flow. I recall (20 years?) figures like 1100 psi before the bypass cut in and 5 gpm for auto based units. I think the pressure would be more or less comparable but flow greater for truck/bus units (just a guess and will defer to jimmci9. I agree with jimmci9 #2 that excess volume/press will just heat up the system and shorten oil useful life. | ||
| Jim and Myrna Lawrence (Daffycanuck)
Rating: N/A |
What I am doing is installing a hydraulic fan drive to replace a jack shaft and a multitude of belts and bearings. I have purchased the motor and pump from e-bay. While making selection, I have tried and come close to matching motor requirements. The pump is a Dowty Tandem series 3000 and the motor a Sauder Danfoss SMN2 with an integrated switching valve. My intention is to control the motor at a constant speed with a line throttle valve. If all works well, I'll replace the throttle valve with a thermovalve. The smaller tandem pump will run the power steering. From what I gather here, it also will be in line with what Marc has mentioned. It will deliver aprox 6.5 GPM but at 3000 psi at 3500 RPM, so I may have to play with it a bit. | ||
| Stan Rating: N/A |
If you are mounting the fan on the motor, you need a motor designed for that use. Standard hydraulic motors will not withstand the pull on the shaft. If you are using the hydraulic motor coupled to the fan shaft it whould work well. Eagle used a hydraulic fan in some busses and someone may have all the technical details on that system. I think they varied the fan speed according to engine temperature. The two busses that I am familiar with were retrofits that were supposed to be copies of the Eagle system. | ||
| Jim and Myrna Lawrence (Daffycanuck)
Rating: N/A |
The motor I am using is the Sauer Danfoss SNM2 motor with Mark 5 Integral Switching Valve. It is the same motor that Sauer Danfoss uses on their Fan Drive. | ||
| Marc Bourget Rating: N/A |
Having participated in a conversation on this point with an automotive engineer who has extensive knowledge of Hydraulic Fan Drives related to interal combusion engines, including the L-10, M-11 and (I believe Cats), I have to ask why would you want to abandon the original system? Repower or just an aversion to belts and bearings? IIRC, the opinion was you go to hydraulic only as a last resort. | ||
| Jim and Myrna Lawrence (Daffycanuck)
Rating: N/A |
I have had the same conversation with a HD mechanic who has a hydraulic system on his conversion...and has for the last 15 years of fulltiming. My conversion is a European Bus that someone has altered the factory cooling system to accomodate an engine swap. The job was not done very well. My jackshaft bearings, fan hub bearings are worn out again. The whole system is out of alignment, so belts are a problem. Why would the hydraulic system be the 'last resort'?? when so many buses on the road today utilize that system.??? | ||
| Ron Rutledge
Rating: N/A |
I too went to a Hyd. fan when I put a 855 Big Cam in My 81 Crown...fan did not line up...Went to what they have on the "NEW School BUS"...I changed the Pump to a "TWO" value body pump from Vicker...Frist...have it set up for your steering then the other line for your fan motor-based on running speed rpm(55-60mph)...I have a therm-temp unit that openes the line at 185...I all so have a hand value that can be turn off in case it fails...I also have a over ride swith on the dash that I can open it on hill's(have not used it) if it heat up...My system run a large tank and 15 gallon of Hyd.Oil and a trans coller from a truck that I put on to cool the oil...It have filter too...It work just fine...no heat so far...Have vicker power sterring pump for sale for a cummmins...Ron | ||
| Marc Bourget Rating: N/A |
The hydraulic systems are not as efficient as the belt and shaft systems, all things considered. A re-power requires compromise and your situation may be one of them. In my father's Prevost re-power to an 8V92, there were all sorts of adverse compromises, including an engine location that dictated the stupid result of installing an 8V71 crank dampener on the 8V92, even then, the belts didn't line up with the alternators, causing frequent failures. To properly align the belts I had to move the battery platform, but the platform uprights were square tubes left open at the top and sealed at the bottoms. They soon would have failed had I not corrected matters. When you have a combined system, you have multiple failure modes for a critical system. You have to answer as to the wisdom of this approach as it's your coach. All may be fine for the next 20 yrs or so, besides the maintenance of the system. It used to be I was anxious for school to get out so I could crawl back under the car. Now I go there with some reluctance having "been there and done that" sufficient to wear out the novelty of doing it for "fun". Doing it so I can have "fun" is still an interest. Onward and Upward | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
...and as I've posted before, I once put a hydraulic fan in my first bus... only to dump it entirely 6 months later in favor of a miter gear/belt drive. It was one of the most hasslesome things I've ever done to a bus... noisy, inefficient, problematic... all "nice" ways to describe how I really felt, which would be much better described with lots of four letter words. Nothin like a good ol' belt drive, no sir...  | ||
| jimmci9 #2 Rating: N/A |
with all the eye-pleasing coverings on most of the earth-moving equipment today, direct drive fans are nearly a thing of the past.... most of the new caterpilar loaders are hydraulic drive engine cooling fans...while i have no real desire to re-engineer the wheel, i think a hydraulic fan drive is very functional....i'm not really impressed with the 100 inch plus belt running a miterbox on the back of my mci9, but it works quite well.... if it didn't i'd seriously consider the hydraulic.. |