My Rix SA-6 Diesel

[tbone1004]

no I meant using a 5-10 horse motor driving a 3 ph generator to make the 3ph for the motor. I doubt that he has 3 ph at his location only 220 1ph from the power line. with larger than 5 hp motor it would not draw the high end per design power from the house. Run the larger motor at half load capability rather than a 5 hp running at say 90% load capacity

use a 2x rated VFD to do the phase conversion. Way more efficient, and much cheaper. I.e. a 10hp VFD to run a 5hp motor. Technically it's sqrt(3), but with the increments that motors and drives are typically sized, 2x is as close as you'll get with small motors. 40hp is I think the first size where you get get away with not sizing 2x by using a 75hp drive instead of an 80hp, but that's also a 200a circuit and is WAY outside of any discussion we have going on here...

 

[NAM001]

use a 2x rated VFD to do the phase conversion. Way more efficient, and much cheaper

I was thinking primarily cost. My rix has bad bearings and I think i crashed a head years ago on it. having problems finding a 3rd party that has the bearing block portion that is made to allow the bearing to be replaced instead of the entire rod assembly and bearing holder or rod end. much like on tractor 3 points wher you can change the bearing to the tractors 3 point pin size.

 

[tbone1004]

I was thinking primarily cost. My rix has bad bearings and I think i crashed a head years ago on it. having problems finding a 3rd party that has teh abearing portion that is made to allow the bearing to be replaced instead of the entire rod assembly and bearing holder or rod end.

VFD's are cheap, motors are not, especially large single phase motors, but you'd still need a soft starter for both the single phase motor driving the generator ,and the 3-phase motor. By the time you do all of that, even if you already have the 3p motor on the pump and the single phase motor laying around you're probably in it for 2x the cost of the VFD. A VFD that does 5hp phase conversion is going to be less than $1k for the nicer ones, about $600 for the normal ones. A soft starter is going to be $320 for the motor. The 3p motor is going to be about $200 cheaper than the 1p motor, so the price difference is not huge.

 

[NAM001]

VFD's are cheap, motors are not, especially large single phase motors, but you'd still need a soft starter for both the single phase motor driving the generator ,and the 3-phase motor. By the time you do all of that, even if you already have the 3p motor on the pump and the single phase motor laying around you're probably in it for 2x the cost of the VFD. A VFD that does 5hp phase conversion is going to be less than $1k for the nicer ones, about $600 for the normal ones. A soft starter is going to be $320 for the motor. The 3p motor is going to be about $200 cheaper than the 1p motor, so the price difference is not huge.

good to know.

i looked at some of his pics and thought I saw a gap in the bearing assy. bad bearing. was looking for a 3rd party source that has eh same block but withthe slots in it to remove and replace the bearing portion with a 90 degree turn and a pull. Its hard to tell by a pic because of shadows etc. asked him to check to see if there was any slop inteh rid movement to verify that. the rod assy is 78 for stage 1 & 2 of them and 400 for the HP one. I found at one time them for very few dollars that were replacable. Im looking at hopefully a 3rd party replacement is available that is cheap so he can replace all 3 together to maintain ballance and keep vibration down.


just looked on ebay and you are right vfd's under 500 for 5 kw drives

 

[Geo7]

I would put the 5hp motor in there and put a VFD on there. Can always slow it down. I think the electric ones are still over 200lbs without a filter stack, so I'm not sure the 20lbs on the motor is going to be significant in terms saving weight.

Current prices are between $2k-$3k depending on area and condition.

That makes sense. I agree the weight difference has no practical advantage in that range, but having the option to run it at full spec is of value. And there is something to be said about maintaining original specs of such a well designed machine, even though I couldn't afford the OEM filter stack...

Good to know about the price range, as the current asking prices I see seem overpriced.

 

[Geo7]

the rod assy is 78 for stage 1 & 2 of them and 400 for the HP one. I found at one time them for very few dollars that were replacable. Im looking at hopefully a 3rd party replacement is available that is cheap so he can replace all 3 together to maintain ballance and keep vibration down.

Thanks for sharing. Often modfications and repairs give the most insight...
If you guys have pictures I'd appreciate it!

 

[NAM001]

working on the pic stuff,,,, I just talked to eric zensius at RIX aND HE IS LOOKING FOR A CONTACT THAT WILL MAKE THESE PARTS. Oops hit the caps lock........ The rix is no longer a military thing but the parts have not dropped the mil spec standards for them. Costs has also not dropped for the parts. I am hoping to find those parts that allow for the floating bearing in it to be easily changed and with a cost of but a few dollars,, instead of the entire rod assembly. rix does not carry the part outside of,,,,,, as part of an assembly,,,,, only other thing other than that bearing component and block is the rod and 2 lock nuts, more or less.

 

[NAM001]

here is a pic of the wabble plate bearing assembly
the bearing assy in itself is the same for all 3 stages only what is connected to them is different. from what I can get it is 78 for stage 1 adn 2 but 400 for stage 3. Per part numbers all that is different is which stage connecting rod is attached to it. Rix dies not carry the bearing assy with out the rods attached. bot mine and the original poster may have a cost reasonable repair if we can get the part.

 

[Geo7]

Thanks, it seems the RIX compressors have great DIY repair potential. And if parts continue to be available, that's great too. But buying a 2nd hand one still means there is a lot to learn and these posts help a lot.

The troubleshooting section in the 1S3B-6 manual list these causes for excessive vibration:

-Loose nuts or bolts on compressor or motor mount.
-Wrong speed (diesel).
-Wrong direction of rotation.​

Do you recognise a worn bearing by vibration as well?

 

[NAM001]

Thanks, it seems the RIX compressors have great DIY repair potential. And if parts continue to be available, that's great too. But buying a 2nd hand one still means there is a lot to learn and these posts help a lot.

The troubleshooting section in the 1S3B-6 manual list these causes for excessive vibration:

-Loose nuts or bolts on compressor or motor mount.
-Wrong speed (diesel).
-Wrong direction of rotation.​

Do you recognize a worn bearing by vibration as well?

there should be a little vibration as well but probably not that noticeable unless you are looking for it. The damage from hammering on the bearing grows quickly. My near first indication was a clattering banging and a shut down. A RIX part replacement ,for the most part, can be done all DIY. the allignments, on the other hand, may not be what most would be willing to undertake on their own. Rix customers would have been much better served if the rod end bearings were designed differently. And every 100 hours changing the bearing and no follow up allignment, if it were a slide in replaceable unit. You just dont do that with military stuff. Profits are at stake.