Sunstar power steering into 7100 series?

[ambler]

I know Al posted that some one had done it. I have the late model Soveriegn installation manual. Has anyone done it? How?

[ambler]

Guess no one has done it, well I'm going to try.

[lndscpr]

let us know how you make out. Sounds interesting

[CarlH]

The SunStar power steering and the later Sovereign power steering system share the steering valve and hydraulic cylinder. You can find the Sovereign power steering parts breakdown in the late Sovereign / 900/ 2800 parts manual TP 400-2218-00-SV-SMA. The Sovereign system uses different mounting brackets and hydraulic lines and other miscellaneous pieces.

[ambler]

Thanks Carl, I have the manuals, but is the dash tower different.

[CarlH]

Only the dash itself is different. The PS dash has an additonal hole for remounting the choke because the current choke location interferes with the PS steering valve. Your current dash can be easily modified by drilling a hole in it. There is an additional bracket that braces the PS steering valve to the dash tower.

[BruceH]

When the steering valve is mounted the shaft for the steering wheel will be slightly off center to the left. The original tower would not work without additonal modification to allow the shaft from the steering cylinder to pass thru it.

[ambler]

That means new dash. I'm reading the install. I hear hydro lines are a tight fit.

[D-17_Dave]

Just bring your stuff down and we'll see if we can't rig up something to work. ;)All the time you've spent working lately you should have some time to play now. Wish you could have made it down to Matt's this weekend. But I know you wish you could have too.

[ambler]

Wish I could have too. I got a call Monday on the way to the airport to fly to LA for a meeting. The Division Chief wanted me to do a meeting back East Friday. Yes Sir I say. I have two sunstar parts tractors for donors, since the 1920s are my primary mowing tractors now. The power steering has me spoiled now, so I want to retrofit my two 7100s. John and I talked and I'll meet my deck tomorrow. I owe you one

[BruceH]

I had new hoses made, 1/4 ID inch I think. The set up works but the power steering lags at times almost like the pump doesn't push sufficient volume even though the engine is running at full throttle. I don't know if the pump is the problem or if the hoses can't flow enough fluid. Perhaps 5/16 hoses would help. All in all, I'm not totally satisfied with the results.

[Al]

Bruce, Now that I think about it, the charge pump may have a thicker gerotor with the PS. Maybe it was changed when they went to hyd lift. Will do some checking. Al Eden

[CarlH]

Ambler, Is there any lag with the power steering on your SunStars? If not, we ought to be able figure out the lag problem on the 7100's since the major components are the same. I have most of the parts to put power steering on both of my 7790's and I would like to have it function well.

[Roy]

My Sovereign with factory power steering lags on quick turns. :( Very frustrating and sometime interesting when you cannot steer fast enough to dodge something (like a tree). Would love to know if Simplicity has a "factory fix" available for the problem.

[D-17_Dave]

Does anyone have the hydraulic shematic or diagram of the Sovereigns w/ PS? Also the flow rates of the charge pump on the diff. model sunstrand pumps.

[ambler]

The sunstar power steering is instant and responsive. You may have air trapped. Install PDF TP_200_2005_02_SV_SMA.pdf

Looks like the hoses t off the hydro lift valve

[D-17_Dave]

Looks like the return line tee's back into the out to tank line from the steering valve. This makes sence. Teeing the pressure line to the lift valve and going to the steering would render both the lift and the steering useless as the oil flow would travel the least resistive path back to the tank. The pressure line from the pump should be deverted to the steering first so it has the priority, then a line from the steering valve marked power beyound should then go to supply the lift valve. Both the steering and lift valves will have an "out to tank" line and this is what should bt tee'ed into to return both discharge lines to the tank.

[BradT]

3yrs ago I bought a factory PS kit #1692856 and just got around to installing it on my 7016H Sovereign. I too am disappointed with the sluggish response and so are my bushes. I've installed new relief valve kits in hopes of increasing the pump pressure but got minimal improvement and sheared the charge pump pin (was worn anyway). Since my 7016H has no hydro lift I just capped off the aux port when I installed the system and used the longer kit hose as the return line to the pump(same ID as the short return). I've heard stories about a higher cap charge pump but my dealer quoted $450+ for a 1685128 pump kit so I'm not too interested. It appears there is a common problem here with these retro-fit kits. Any thoughts? I might add it does look like a factory installation and was not difficult to adapt to the earlier style frame.

[roma3112]

fellas i am not sure if this will help any of you but i have one of the last batches (according to what the factory told me when they replaced my engine)of sovereigns built. my machine has ps and hydro lift; I have never had a complaint about the responce of the PS. I am not sure if i can get any numbers off the pump or any place else that may help you folks. if i can be of assistancce let me know.

[Roy]

Anyone know what the AUX (auxiliary) port on the steering valve is for? My Sovereign has factor hydro lift and PS but the AUX port is unused.

[UCD]

BradT I think your problem is that your tractor didn't have hydro lift. Not haveing hydro lift the pump dosn't have the higher pressure relief valves in it that that a tractor with hydro lift has. In order to install hydro lift on a tractor with out it the pressure relief valves need to be replaced.

[HubbardRA]

Maynard is correct. If the tractor didn't have a hydrolift, then the relief valves are set up wrong. I put a hydrolift on my 716H. It would work somewhat (slow response, nowhere near enough lift force) till I installed the extra relief valve (is not used for non-hydrolift) and changed the spring in the existing relief valve. If you do like I did, and go to Simplicity pubs, then look up a 7116H, there is a breakdown for hydrolift and non-hydrolift trannys. This will tell you the difference and what needs to be changed. They talk about a shim in the parts breakdown. This is really a shim kit with several thickness shims. To max out the system, you can hook up a pressure gage and by changing the shim thickness, boost the pressure to the max allowable. This should give you quick, responsive steering. Remember, I am talking about looking up the check valves for a "hydrolift", not power steering. The power steering is normally added to units that already are set up for a hydrolift.

[D-17_Dave]

quote:

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Originally posted by Roy
Anyone know what the AUX (auxiliary) port on the steering valve is for? My Sovereign has factor hydro lift and PS but the AUX port is unused.

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Roy, you mentioned in a prior responce the delay in your steering. You may have answered part of the problem by pointing out how yours is plumbed. The outlet on a steering valve needs to go to the tank uninterupted. As flow is directed into the steering cyl. by the valve the low pressure side of the cyl. displaces oil that returns through the steering valve and must go back to the tank. If this flow is asked to do other work, such as go on to the lift valve or pass through any series of fittings that might restrick it's flow it will cause back pressure against the pressure comeing from the charge pump thereby diminishing the flow and pressure that would otherwise be used for the steering. The AUX. port is the same as the power beyound port. This is the port used to let the extra flow not needed for steering to be used down stream of the steering valve such as the lift valve. This port gives 100 percent priority to the steering when you make a turn. When your not useing 100 percent of the flow, what's left over is directed out the aux port on to what ever else downstream is needed and can provide full pressure without impeding the useage of the steering valve. In other words, if your lift valve is plumbed after the steering valve from the out to tank line any pressure no matter what it is would be subtracted from your input pressure. It may not take much pressure to flow the oil back to the tank but remember the charge system is only around 500PSI on these pumps. If it takes 25 psi to return the oil flow through the lines and fittings you'd have to subtract the 25 from the 500 to get the avaliable useable pressure. Now lets look at one more thing. If you use this the way it's plumbed and hit the lift valve untill the cyl. bottoms out it will stop the flow of oil and force the flow over the relief valv. This will effectively stop the flow of oil to the steering and lift valves internally inside the pump untill you release the lift handle allowing flow to resume. When this happens you will lock the steering due to no oil flow at all. That is if the lift valve is plumbed to the outlet of the steering valve. Some try to plumb the power out from the pump and TEE into the pressure line. This is also incorrect. Presurized oil flow is like electricity, it follows the path of least resistance. Therefor if the pressure line is TEE'd into whatever is the least path of resitance back to the tank is the path the oil will flow. If you use the flow for steeing the oil will sence the applied load from the steering valve and flow more through the lift valve, and vise versa. The only way for the entire system to act properly is to have the correct relief valves in the pump as Maynard described. Understanding that there is multiple relief valves used as the charge pump just pumps. That's all it knows to do. It's pressure is controlled by the internal plumbing of the pump and the relief valves controlling each branch circut. As the charge pump pushes oil into the houseing the high pressure circut of the hydrostat pulls off whatever flow it neds first. This is how the first circut is designed and is rated at whatever predetermined spec the they want for the master charge pressure. Unused oil flow is then ported to the lift/steering aux flow and is controlled by a secound relief valve for this circut. It's slightly less than the first circuts max pressure so it has no chance of backing up and affecting the first circut. This is the basis for my question on what the specs were for the sunstrand pumps in the RBT's. I know that the master charge pump pressure is around 500PSI +/- 25psi on the powermax's with only around 3.5 GPM rateing. This(plumbed properly) has proven to be a plenty to run the P/S on my 620. I don't know if it's the same on the large frame tractors but I feel like it would be close to the same peramiters. Some things that will affect the responce of the steering would be the displacement of the steering cyl. The larger the displacement the easier the steering will be to turn the steering wheel but the more flow will be required so it wouldn't be as fast. On a RBT you shouldn't need a large cyl. to turn the steering with as little load and weight that is on these tractors. But if you go too small the steering would be so responcive and jumpy you would have a hard time controlling it. I hope I've made sence here with all this. It didn't take me but 10 years to understand it all and be able to apply this homeade engineering to these tarctors.:o):D If anyone has questions on the theories or the general application of hydraulics pm me or give me a ring and I'll be happy to try to walk you through what I can. I claim to be no expert or anything on any of it. Rather I have had several years of practicle field experiance with different systems. Understanding the basics of what components are supposed to be used for helps me figure out how to use them here and apply them to our needs.

[HubbardRA]

Dave, If my feeble memory is correct, the pressure for the hydrolift (first relief valve) should be somewhere between 650 and 730 psi, and the pressure for the tranny (second relief valve) only runs at about 225 to 275 psi. This is from the Sunstrand charge pump on a 7100 series tractor. As I said, this is from memory, not from a manual, and only to illustrate the difference in the check valve pressures. When changing the relief valves you can verify this by the significant difference in stiffness of the springs in the two valves. Mike (MDB) installed power steering on a tractor for his Dad. I think he said that he said it came to the steering valve, then back to the hydrolift before returning to the tank. Roy's steering system may have been plumbed wrong. From the way I understand it, the only "T" connection should be the return lines from the control valves to the tank. The pressure lines should have been run thru the steering valve, then to the hydrolift. They should not have been hooked up in a "T" configuration.

[BradT]

When I installed the PS kit I replaced both charge relief valves but not the two check valves. The lower relief valve port actually had no valve in it just a plug because my 7016H had no hydro lift. I noted the spring in the lower kit is a lot beefier than the upper kit. I have no access to a pressure gauge so I started with no shims (no improvement) and then went to one thick shim with slight improvement(broke my charge pump shear pin after 20 min). I got a couple of pins on order and will try a thinner shim next time. The installation instructions used the same diagram shown above and ran the aux port line I believe to the lift control valve inlet. Should the shims be the same thickness on both valves or is that irrelevant to the problem? I'll report back once I get the pump back on and try reshimming.