CBR Steering Pumps - OEM Applications?

[Fwjeep]

Calculated with .66 cu in per rev.
.66xRPM/231

let me double check my numbers

800rpm x 7.5in pulley, divided by 5.5in equals 1090 pump rpm

.66x1090rpm = 719 cu in /231 is 3.11gpm

 

[AgitatedPancake]

Hmmm alright cool. I really want to tinker with a CBR, but I haven't got a confident feel on exactly how much bigger their displacement is than these TCs yet.

I got tired of trying to remember to calculate all the variables for each one of our scenarios and examples to really get a grasp on the big picture so I threw them into an excel doc for easier viewing. Two different pump pulley diameters, unregulated pump volume at various engine RPMS, and lock to lock speed depending on the volume of your steering system and the engine speed.
-This is essentially my setup, with a .64 cu/in displacement for the TC pump I've seen discussed, that seems to correlate to my timed steering tests earlier today.

 

[Provience]

current real measured numbers with the theoretical 0.66 cu in pump and the real 5.5" pulley are approx. 4 seconds at idle, 3.5 seconds at 1500 rpm and 3 seconds at 2000 rpm.

so somewhere it's pretty far off. 3.87 is basically 4, but is 2.9 at 1,000 rpm really comparable to 3.5 at 1500 rpm or 3 seconds at 2000 rpm? assuming that ~1700 shaft rpm is at or near all in on the regulation of the pump

 

[AgitatedPancake]

current real measured numbers with the theoretical 0.66 cu in pump and the real 5.5" pulley are approx. 4 seconds at idle, 3.5 seconds at 1500 rpm and 3 seconds at 2000 rpm.

so somewhere it's pretty far off. 3.87 is basically 4, but is 2.9 at 1,000 rpm really comparable to 3.5 at 1500 rpm or 3 seconds at 2000 rpm? assuming that ~1700 shaft rpm is at or near all in on the regulation of the pump

My speculation is it's already getting flow regulated somewhere around 1k if it's really pushing 3.78gpm. With my testing today I was hoping to get a distinct feel for where the flow regulation is actually kicking in, but the numbers weren't fine enough to tell. Also note that I'm turning lock to lock with one hand and holding my phone as a stopwatch with the other, so assume my timing estimates are pretty loose.

 

[Provience]

My speculation is it's already getting flow regulated somewhere around 1k if it's really pushing 3.78gpm. With my testing today I was hoping to get a distinct feel for where the flow regulation is actually kicking in, but the numbers weren't fine enough to tell. Also note that I'm turning lock to lock with one hand and holding my phone as a stopwatch with the other, so assume my timing estimates are pretty loose.

you need a neighbor kid with a stop watch

 

[Fwjeep]

[No message]

 

[Fwjeep]

Have you considered adding the extra hole in the fitting to increase idle flow?

 

[AgitatedPancake]

Haha right Province. At least the numbers should be good enough for us to ballpark the concept, but yeah should be expected to be pretty coarse data points.

Have you considered adding the extra hole in the fitting to increase idle flow?

I have not. Though my current feeling is the flow valve is cracked open off the fitting already by some small amount while sitting at idle? It just doesn't go far enough backwards in its bore to open the relief port until slightly higher flow rates

 

[AgitatedPancake]

Alright, I need to turn my brain off hah. Added a bit more to this excel doc to have flow regulation and a chart to help visualize. I have the flow control assumed at 90% effective which seemed ballpark close to the eaton chart I was looking at the other day, but I'll probably hone in on that as a good starting point. But you can set the flow control GPM as a variable, so the chart shows the pump outputting 100% up to that point before it kicks in and stabilizes things.

 

[AgitatedPancake]

Alright I think I've got a version worth sharing. It's an excel file. Green cells are variables, adjust as you wish for your configuration. And for clarity, steering system volume is the total volume it takes to go lock to lock (so steering box piston surface area x throw, plus ram working surface area x throw). The math should all be right, but let me know if you find any issues and i'll update.

https://alpinepeakprecision.com/tech/steeringpump/PS Pump Displacement Chart - V1.xlsx

 

[RadialDynamics]

Good to see people that get it, nice work. Since there is so much talk about pump displacements, here is what I have measured and know to be true to help you guys keep your numbers accurate:

- TC pumps: 0.64 in3 (10.5cc)
- SPX-1/CBR XR race pump: 0.67 in3 (11.3cc)
- Cast iron CB pumps including my CB-X series: 0.80 in3 (13.1cc)
- P pumps: 0.95 in3 (15.6cc)
- CBR pumps: Varies... I have found everything from 0.67in3 to 0.95in3 in the ones I have opened up including new and rebuilt PSC models
- "Trophy Truck" pumps (based on a Saginaw big bearing model referred to as P235 although they go by a few names): 1.22 in3 (20.0cc)

 

[AgitatedPancake]

Good to see people that get it, nice work. Since there is so much talk about pump displacements, here is what I have measured and know to be true to help you guys keep your numbers accurate:

- TC pumps: 0.64 in3 (10.5cc)
- SPX-1/CBR XR race pump: 0.67 in3 (11.3cc)
- Cast iron CB pumps including my CB-X series: 0.80 in3 (13.1cc)
- P pumps: 0.95 in3 (15.6cc)
- CBR pumps: Varies... I have found everything from 0.67in3 to 0.95in3 in the ones I have opened up including new and rebuilt PSC models
- "Trophy Truck" pumps (based on a Saginaw big bearing model referred to as P235 although they go by a few names): 1.22 in3 (20.0cc)

Oh man, that is great info. And I definitely have you to directly thank for helping me grasp exactly how the flow control system works, very cool stuff all around. I wouldn't have got to this point oif being able to offer this to the community without you helping me understanding it all!

 

[Fwjeep]

Good to see people that get it, nice work. Since there is so much talk about pump displacements, here is what I have measured and know to be true to help you guys keep your numbers accurate:

- TC pumps: 0.64 in3 (10.5cc)
- SPX-1/CBR XR race pump: 0.67 in3 (11.3cc)
- Cast iron CB pumps including my CB-X series: 0.80 in3 (13.1cc)
- P pumps: 0.95 in3 (15.6cc)
- CBR pumps: Varies... I have found everything from 0.67in3 to 0.95in3 in the ones I have opened up including new and rebuilt PSC models
- "Trophy Truck" pumps (based on a Saginaw big bearing model referred to as P235 although they go by a few names): 1.22 in3 (20.0cc)

Thank you!

 

[HYDRODYNAMIC]

I'm interested to see how the flow is at the higher RPM range when cavitation starts to ramp up and calculated displacement does not match actual. I would assume that it would be different for each systems plumbing style and restriction levels.

 

[AgitatedPancake]

I'm interested to see how the flow is at the higher RPM range when cavitation starts to ramp up and calculated displacement does not match actual. I would assume that it would be different for each systems plumbing style and restriction levels.

Agreed. Radial had some interesting notes from the discussion between you two earlier in this thread about the losses as the RPMs got higher, that's the only reference I've seen with numbers. But like you noted, I'd expect every setup to be different. Especially with all the different variations in how much flow recirculation there is, and reservoir setups

 

[RadialDynamics]

I'm interested to see how the flow is at the higher RPM range when cavitation starts to ramp up and calculated displacement does not match actual. I would assume that it would be different for each systems plumbing style and restriction levels.

With flow-regulated pumps I find that once the flow control setpoint is reached, the flow rate output from the pump stays pretty consistent up to high RPM. With non-flow regulated pumps, as I had described previously, they eventually hit a wall and the flow rate where that wall exists depends very much on the setup. I should probably clarify though that the displacements I provided above were not based on measuring flow and RPM, those are the actual displacement volumes of the pumps calculated from the dimensions of the cam ring and vanes.

 

[AgitatedPancake]

Alright I have another question related to all of this: Fluid choice.

I'm sure there are different traits and viscosities between PS fluid, ATF, hydraulic/tractor fluid etc and all the other varieties people run. I could see lower viscosity being nice because it would provide less resistance passing through restrictive orofices in the steering system, but may have higher losses past the vanes in the pump. How about anti-foaming properties? I know the grand cherokees with the hydraulic fan ask for a specific fluid in factory form compared to the standard non-hydro fan jeeps, but the difference has never really been articulated.

This is another subject where I don't know what I don't know, so I'm curious to hear the thoughts from all of you with more experience than I!

 

[Provience]

quoting myself from post #26 of my complex hydro thread regarding fluid

edit2: just taking on some notes from Danfoss

Oil temperature Oil life will be drastically reduced because of oxidizing if the operating temperature exceeds 60 °C [140°F] for long periods. A rule of thumb is that oil life is halved for each 8 °C [46.4°F] in excess of 80 °C [176°F] . Impurities in the oil, e.g. particles or water, will further reduce its life.

min. rec'd oil temperature 86*F

viscosity rec'd 12-80 mm2/s = ISO 12 to 80, or ISO 15 to 68 to stay within limits oil grade

Oil temperature Oil life will be drastically reduced because of oxidizing if the operating temperature exceeds 60 °C [140°F] for long periods. A rule of thumb is that oil life is halved for each 8 °C [46.4°F] in excess of 80 °C [176°F] . Impurities in the oil, e.g. particles or water, will further reduce its life.

min. rec'd oil temperature 86*F

viscosity rec'd 12-80 mm2/s = ISO 12 to 80, or ISO 15 to 68 to stay within limits oil grade


and this is why crisbee1 recommended previously Mobil DTE 25 with it's fancy pants ISO 46

i've always been kind of curious what "too hot" actually is for hydraulic oil and such, temporary over 140 isn't bad, 180+ is bad, change the oil eventually. makes for a good reason to put a system together and run it for a bit while monitoring the temperature in, say the reservoir, and seeing what it is actually doing.

VISCOSITY CLASSIFICATIONS (premiumgrades.com)

ISO derivations.

 

[AgitatedPancake]

Solid info, thanks man. I see you have a viscosity called out there, what dictates that? Do vane pumps and gear pumps want the same fluid?

I just installed a 4.5" pulley to replace the 5.5" pulley on my Grand Cherokee hydro fan TC pump, and I got some cool results that also helped confirm the accuracy of the calculator in my mind.

Here are my lock to lock times at different RPMs with the two pulleys:
Engine RPMs, 5.5" Pulley, 4.5" pulley
......600.................4.2............3.5
....1000.................3.5............3.0
....1500.................3.0............2.75
....2000.................2.8............2.5

Plugged into the calculator, I get very similar numbers which is an awesome confirmation. The only discrepancy is down at idle, but I'm OK with that until I understand better. It's very possible my tach is off by 100 rpm and i'm actually idling 700, which would make things coincide. I had to play with the GPM cutoff to find the rating that coincided the most, it looks like my 5/32 orofice hole flows somewhere around 3.75 GPM before bypassing

 

[Provience]

I just went through the steering valve catalogue until i found what it wanted. figured it was the most expensive part in the whole system, so probably need to keep it happy

most things are pretty fluid tolerant, like cylinders and gear/vane pumps. 2 biggest things are viscosity based on air and operating temperature ranges and seal types. most everything seems to be built around dinosaur based goo and anybody looking to switch to plant or science based goo should consult the part mfg and change out all their seal types to ensure compatibility.

as long as their is minimal debris (use a filter) and minimal cavitation (use appropriate suction hoses and ports), pumps will pump water to grease.

guess i should see if saginaw puts out a viscosity range for their pumps

 

[Provience]

here is a mfg spec from TRW regarding their EV pumps, which are vane pumps similar to everything else. they don't list a viscosity rating or anything of the sort and say

"fluids approved and recommended include: ATF Dex II, III, Mercon, +4"

so, whatever you've got for standard. anything else, give them a call to see if it is compatible with the case/shaft seals.

ev-pump---trw1313.pdf (trwaftermarket.com)

EV Pumps (trwaftermarket.com)


edit: just for kicks, Royal Purple Max EZ is a ISO 48 which is very similar to mobil DTE 25 and claims to have a temperature larger range. Per gallon, RP is ~$60 and DTE 25 is ~$40 and ATF III is ~25-30
RP-PDS-Max-EZ-2019.pdf (royalpurple.com)

 

[AgitatedPancake]

Nice, it sounds like the consensus is pretty much don't stray away from the common options haha.

Alright I've got a theoretical question for the day - can you stack flow control valves without too much repercussion? I assume they create a certain amount of resistance/backpressure, is that negligible or pretty notable? Here's my theoretical reasoning - I want the most volume possible at idle, let's say 4gpm, but I have no desire for any increased flow at higher RPMs. If our integrated flow valves are somewhere around 90% effective (which they seem to be), I still gain over 2 GPM of flow before red line. I'd rather that number be lower. if I left the internal regulation, and added an external flow regulator at say 4.2, if the second regulator only sees a 4-6 GPM sweep and diverts 90% of that excess, the red line would only be 4.4gpm

Not that I'm going down this route as I think it's manageable so far, I'm just curious

 

[Provience]

you could, the extra cost would be adding in a bit more resistance for that valve. I honestly don't see much benefit for it though. you'd have all the extra cost and line's of going full external regulation with just a fraction of the benefit

with the smaller orifice valve, are you still getting the same level of steering sensitivity related to RPM that you were getting with the larger orfice/unrestricted? 4-6gpm is much better than 4-10 and then starving the pump.

more flow at idle requires more volume, there's just no way around that.

 

[Provience]

that's where the 2 pump comes in to play. 2 @ 2.5 or 3 gpm internally regulated, which is super easy and normal for a standard pump to handle, will give you close to 4 gpm at idle and then hit the regulated 5 or 6 gpm fairly quickly. yeah, you still get the loss and such and whatnot, but what is the tradeoff worth.

hence the high flowed increased volume CB-X pump that does it in one shot

 

[AgitatedPancake]

you could, the extra cost would be adding in a bit more resistance for that valve. I honestly don't see much benefit for it though. you'd have all the extra cost and line's of going full external regulation with just a fraction of the benefit

The benefit I'm going for is just the fact that the efficiency of one single flow relief isn't enough to keep those high RPM flows in check. But that issue rears its head whether it's an internal or external valve. If I'm configured to get 4gpm at idle with a single flow control device, I'll be at 6gpm in the higher RPM range. which means I'm getting 50% more volume than I actually want when the engine is up there. So if I were to add a second flow control downstream of the first, the first sees from 4gpm-20gpm through the RPM range, but the second only sees 4gpm-6gpm through the RPM range, and at 90% efficiency it would purge ~1.8gpm of that excess 2gpm I don't want. So my full sweep from idle to rev limit would only be 4gpm-4.2gpm, huge improvement.

I'm not saying it's worth doing or not at this point, but that's the theory behind the thought process

 

[Provience]

valid


edit: that is where the fancy higher end pressure compensated flow control valves come in to play, they will keep you at a 10-20% swing (depending on mfg rating) through a larger range of input flow

edit2 - dual flow control valves is about where i'm heading with using a load sense valve

 

[PAE]

To those in the know, what would be wrong with a gear pump with a bypass valve when it gets to XXXX PSI ?

Thanks for the replies.

 

[Provience]

To those in the know, what would be wrong with a gear pump with a bypass valve when it gets to XXXX PSI ?

nothing, specifically.

the biggest concern with a gear pump and a pressure relief valve is that you lose all control over flow and your steering may be subject to changes in sensitivity/feel substantially.

the other concern is a need to upsize your fluid lines to handle the additional volume without starving the pump or stressing the fluid.

the other concern is the potential for significant parasitic loss sending a rather large volume through a restriction, be it in the steering box or elsewhere.

that said, thousands of people run a gear pump with a bypass valve and are plenty happy with it. in fact, it's the standard in many circles.

 

[AgitatedPancake]

I just stumbled on a gem of an article I had no idea about. Ford VAPS system. Variable Assist Power Steering. It uses vehicle speed and one other input to decrease assist at higher road speeds. It looks to be an electronically controlled valve on the high pressure line. Now i need to investigate a little deeper

https://www.aa1car.com/library/2004/bf10434.htm

 

[Provience]

yeah that's been out for a while and somebody...honda or gm? was doing variable steering with speed with an electric setup. been a while, so details are foggy