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Brettw

Dual brakes / pedals question

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Brettw
I am a bit confused on something. What is the reasoning behind dual brake pedals and independent rear brakes on the Sunstars? I understand the usefulness in a farm tractor, helping to shift traction or to expedite turning, but when the brake/s on the Sunstars are applied it returns the hydro lever to neutral. So what is the point / advantage of the dual braking? I may be a bit challenged here and am missing the obvious.:o)

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MysTiK
The wording I read was about applying one side - "partially disconnects the hydro". or like that. Maybe the manual is helpful, dunno. When I bought my 716H, I called the dealer with question about brakes on that unit (not quite working). He said "You don't need it. Don't use the brake. It's bad for the hydro." Basically the hydro stops, and if you dump the clutch/brake at full throttle, you just SLAMMED your hydro. Great for drag racing; but what about longevity? I never use my brake - except for starting. It only barely makes contact anyway - no brakes, use the stick. period. This was shocking news for a scared nooby. Unless you have 2 hydros, I can't see how "partial disconnect" could even happen on one side only. Unless there's some trickery in the rear end somehow. And that sounds like a zero turn. Great question. I hope there's more discussion on this.

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D-17_Dave
All these tractors have a differential so applying one brake in a sharp turn will aid in turning. The harder you apply the brake the shorter it should turn. The dual brakes on my 720's don't reduce the hydro, didn't know the Sunstars did that. Likely a home owner control so someone who isn't familiar with this setup won't brake and use a heavy hand on the hydro at the same time. I'm sure there should be some way to disconnect this feature.

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MysTiK
Sunstars have drum brakes rear. So (disconnect hydro) is wrong; brake just slows one wheel, and compensated by the differential - seems more logical. Like Dave said. I don't know where I got that partial disconnect idea - maybe a sales brochure. Here's a bit of info: from the Deutz brochure: http://www.simpletractors.com/deutz/1920_%26_1918.htm It's still doesn't quite answer the question.
quote:
9. Heavy-duty adjustable self-energizing brakes. Large automotive drum type, with more braking capacity than band brakes. When depressed, brake pedal(s) automatically move hydrostatic drive control toward neutral. 9A. Dual brake pedals on the 1920 can be locked together, or used separately for sharp turns. Provides smooth, effortless braking control.
So it reduces hydro speed - that makes sense. How much?? It's not using the clutch to disconnect hydro. Either brake, or both brakes, will move hydro towards neutral. = Is there a clutch/brake? As in Sovy tractors? = The tractor slows, which seems ok, since you hit the brakes. = Does it stop? How do you stop the tractor? = Is stopping a hydro function? or a brake function? or both? = Will more brake pressure push hydro into full neutral position? Who drives a Sunstar? we need answers.

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Brettw
quote:
Likely a home owner control so someone who isn't familiar with this setup won't brake and use a heavy hand on the hydro at the same time.
quote:
"You don't need it. Don't use the brake. It's bad for the hydro."
Yes, likely an engineered nanny of some kind. And yes again, brakes on these hydros are almost a mute point unless an emergency requires a sudden panic stop, or for use as a park brake. And it seems they are usable and therefore probably useful on the 720 / 4040 Powermax series. BUT then the question remains and is even more perplexing, why put a big setup of dual brakes on a tractor that can't really use them for any real advantage? You can't use them to aid in turning, you can't use them to transfer wheel spin (not to mention these tractors were also available with a diff lock, so again no need for dual brakes to help with wheel spin). Seems like an added expense, or a overkill park brake, or a sales gimmick, or more likley for reasons I am too simple minded to figure out. I really am curious.

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MysTiK
The part I don't get is where SUPPOSEDLY the hydro tends to neutral - is that a nanny? bizarre. I am hoping there's more to it than nanny - but I dunno. Anyway the neutral tendency just seems like a disruption to normal driving. After braking, one has to reset hydro to desired speed?? that's a disruption to me. - gotta be more to it than that. How is this different on a full size tractor? what's the setup of those? I have driven a couple, not much tho. But I never saw speed controls affected by braking - or did I miss it...? I do know I did not miss the tree I tried to drive under... :D

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maxtorman1234
I've just started using the rear brakes on my Ultima when mowing the lawn, very handy for turning sharply around the trees. If properly adjusted, it will reduce they hydro to about 1/2 speed. When locked together, they hydro does return to neutral. The only down side is that the wheel locks up and is actually dragged around by the machine. Not a problem in my case as we spray around our trees. The brakes do help a lot for steering. I just picked up another Ultima, and the roller that returns they hydro to neutral was missing, using the brakes to steer at full speed is quite a ride.

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Brettw
So Graham, what you are saying is used individually it will slow the hydro, but not stop it thereby aiding in turning. if both are locked together it will bring the hydro to the complete nuetral position. This makes sense now. The brakes can be used for aiding in turning or stopping wheel slip if used individually. THAT is the answer to the question. Thanks for the help. Those of us who are challenged need it.:o)

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SmilinSam
The braking system on the Sunstars also puzzles me. I just put the dual brakes on my project in place of the single brake. The inboard brake controlling the left brake also returns the motion lever to neutral. This is whether the brake is individual or locked together with the right brake. What this means to me is that you really only have the right brake to use to aid in right turns. Try that with the left brake and you just end up stopping the tractor. Am I missing something here?

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babablacksheep
Hi. I can see the brake reducing the motion lever to half. If you are trying to turn tight enough to need the brake, you probably shouldn't be doing it at full speed. I can also see the locked brakes moving the motion lever to neutral, it's great for a panic stop because you don't have to take a hand off the steering wheel to move the motion lever. One brake should not move the motion lever to neutral. Either something is out of adjustment, or the engineers really goofed.

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DanD
From the Sunstar owner's manual: Check out upper left corner of page 17 of the PDF file (page 15 according to the numbering in the manual itself). [url][/url]http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=ifDzFO9buH0sF9DOh6lEP5NRQpe

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Brettw
Sam, Having looked over the brakes on this one now, and really observing how the hydro / left brake / right brake contraption of levers and rods, etc. works, I think there is an adjustment issue with your setup. On this tractor left and right move a gate in opposite directions, both of which return the hydro to about half level. Pushed together they return it to nuetral. So it does appear to work exactly as Graham had stated. At least on this bucket-o-bolts.

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SmilinSam
Looks like the single brakers return it all the way to nuetral. I am assuming the dual brake setups use the same guide plate , but a different rod or something, of which I dont have at the moment. Will have to dig around in the manuals to see ..

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Brettw
Actually, those of us who don't take the time to read, might just want to look at he decal right between our legs. It states all about the brakes and how they work.OO I feel so brilliant right now I can't quite explain it. If you are speaking of the Sunstar braking setup, Sam, then I have to believe something isn't right in your adjustments / setup. After just a few posts and some well received insight, I am now a professed genius when it comes to these brakes............or maybe not.:o)

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SmilinSam
What isnt right is the parts . I didnt get some of them with the dual brake pedals I got. Single brake system uses a single rod to the neutral plate while the dual brakes use a pair of rods, one for each pedal, to the plate. These two rods attach to a pivot bracket that bolts in just under where the single rod would on the neutral plate. When the brake pedals are locked together the plate is pulled from the center pivot point in unison. When pedals are used individually, the pivot plate drops an inch or so before it starts pulling on the plate to make it go to neutral. That way it does not have enough travel to take it all the way to neutral. All I need is the correct parts, or measurements of the two rods for length and the pivot braket for length and I'm all set.

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MysTiK
Brett, anything I said was best guess and speculative. If you or anyone else fully understands this, then I would rather hear that. Or maybe it's still in motion. The good news is that more people with experiences are involved in it now; and the ideas are largely similar. Sam, when you say neutral plate, do you mean that part of the trans, or do you mean the lever position, where neutral is the middle slot. I think you mean the C-shape part on the Sundstrand trans. where "neutral adjust" and "reverse creep" are worked out. This is quite fascinating. Someone mentioned setup for this system; if it's adjustable, then it's tweakable perhaps, and personal preference could perhaps be "dialed in" - what a concept. If that's true, then this has moved from tedious "nanny" status to preferential rocket science. [sm01). I don't have access to a sunstar, never did, but I have long admired them, just because because. like the name. [8)] But there's some serious engineering in these things.

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SmilinSam
The plate is properly called " Hydro lever Cam Plate", part #1674419 in the parts manual I am looking at. The dual brake tractors use 2 "Ground speed brake rods" part number 1674236 in conjunction with and attaching to "Pivot plate" part number 1676823 which then connects to the above cam plate. Single brake tractors use only "ground speed brake rod" 1674732 to attach directly to the cam plate.

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MysTiK
quote:
Originally posted by SmilinSam
The plate is properly called " Hydro lever Cam Plate", part #1674419 in the parts manual I am looking at. The dual brake tractors use 2 "Ground speed brake rods" part number 1674236 in conjunction with and attaching to "Pivot plate" part number 1676823 which then connects to the above cam plate. Single brake tractors use only "ground speed brake rod" 1674732 to attach directly to the cam plate.
There it is. Thx, Sam. The sweet sound of accurate information.

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MysTiK
- those parts diagrams are really hard to follow - the parts manual I have uses 2 separate diagrams to illustrate it. I have parts and ops manuals now. In the ops manual, it doesn't take much reading to discover that a 20hp Sunstar is a very different animal to a Sovereign. Also, I didn't pursue it; but I think the lower hp models MIGHT be more similar to a Sovereign, since it's the extra features that add complexity. This is one case where RTFM (read the manual) definitely applies; and if you don't want the complexity, you don't want the relative hi tek of the 20hp models. Opting for 18hp models should be more user friendly. The 20's are serious because of the extra built-in features. Loaning it out to a friend, etc., might not be the thing to do. The 20's have 2speed hilo rear end with a shifter that includes neutral, for pushing the tractor. They seem to suggest using lo range for Working, and using hi range for Transport function. And they issue a warning about the brakes when transporting at high speed - use both pedals - due to sudden turn, sudden speed reduction, if use only one pedal. Also found other items of interest. deck leveling front-rear angle adjustment available and spelled out, larger tires require deck in taller mow height to raise deck and clear rollers/tires. There's probably lots of other interesting stuff for your reading enjoyment. It seems that manuals are combined to cover all models, at least the ones I saw - same info, different MFR's. The one I downloaded was called a 'replacement manual'. Covers all 'horsepowers' and all brands.

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MysTiK
Apart from the various linkages involved in the dual pedal system, there is also a "star adjustor" on these automotive style brakes. I didn't see anything in the manual about tweaking brake responses, or neutral trans responses. I thought perhaps the star adjust could be used to reduce hyper brakes; making them more predictable, for personal preference. I don't know if the hydro linkages allow personal adjustments. Had to stop reading the manual, for now. sm01

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SmilinSam
quote:
Originally posted by Brettw
Sam, I can measure up the parts you are missing, let me know the numbers.
Found a rod, so I can make the second from copying it. All I need is measurements for the "Pivot plate" part number 1676823 . Thats the rectangualar plate with three holes. Pivots on the center, and the two brake rods attach to it at the outer holes. Should be visible from the right side as seated with side panels off.

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CarlH
Good news: found 3 rods and 3-hole plate in my SunStar parts box. :) Bad news: did not find actuating lever I bought on eBay sm02 Sam, I will measure the plate tomorrow.

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1Litre
I just tested out my Sunstar and each brake pedal pulls back the hydro lever about 50% forward motion. It also works in reverse. I was in the gravel drive and performed the left wheel brake turn and barely made a difference . I had applied the brake hard and the left hand wheel continued to rotate. I can count on one hand the use of the brake on this unit . I use them as parking brake when on a hill.

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