Help Needed. Automatic Return to Neutral for New Hydro Pedal

[wallfish 16,748]

7 minutes ago, Handy Don said:

The hole positions you mention might have some effect but it’s tough to determine exactly. The trick is managing the intersection of the arc traced by the follower with the arc at each point of the V as the follower moves. You might just want to post some measurements for the full forward and reverse positions as well as the neutral position. Then its just arithmetic!

See what I mean? I just realized I have no idea what Don says!

[Handy Don 11,861]

2 minutes ago, wallfish said:

See what I mean? I just realized I have no idea what Don says!

Oops. 

[Bill D 1,827]

12 minutes ago, Handy Don said:

You're welcome.

Re-doing the pivot may help the clearance issue, as well.

 

The hole positions you mention might have some effect but it’s tough to determine exactly. The trick is managing the intersection of the arc traced by the follower with the arc at each point of the V as the follower moves. You might just want to post some measurements for the full forward and reverse positions as well as the neutral position. Then its just arithmetic!

Neutral center to center is 4 1/8".  Full forward is 5" center to center.  Reverse is 3 1/2" center to center.  Thanks for the help.  I'm terrible at math.

[Handy Don 11,861]

1 minute ago, Bill D said:

Neutral center to center is 4 1/8".  Full forward is 5" center to center.  Reverse is 3 1/2" center to center.  Thanks for the help.  I'm terrible at math.

Distance from return arm pivot to the center of the V? Width of the V?

Edited September 24, 2023 by Handy Don

[Bill D 1,827]

1 minute ago, Handy Don said:

Distance from return arm pivot to the center of the V? Width of the V?

Pivot to center of the V is 4 1/4".  Width at the top is 2 3/4".

[Bill D 1,827]

I'm thinking that moving the pivot point to the bottom would probably make things worse? 

Edited September 24, 2023 by Bill D

[Handy Don 11,861]

26 minutes ago, Bill D said:

I'm thinking that moving the pivot point to the bottom would probably make things worse? 

It looks like you moved the pivot up to get it away from the belt but kept the two arms very close to perpendicular to each other when the follower is at neutral. Good!

If you are satisfied with the performance of this setup for getting forward motion and having it return to center effectively, then IMHO adjusting the slope of the reverse side of the V shallower (a bit at a time) is the easiest way to get close to the same performance for reverse.

Will that return control arm be strong enough to not bend at the point of the V?

 

 

 

 

[Bill D 1,827]

2 hours ago, Handy Don said:

It looks like you moved the pivot up to get it away from the belt but kept the two arms very close to perpendicular to each other when the follower is at neutral. Good!

If you are satisfied with the performance of this setup for getting forward motion and having it return to center effectively, then IMHO adjusting the slope of the reverse side of the V shallower (a bit at a time) is the easiest way to get close to the same performance for reverse.

Will that return control arm be strong enough to not bend at the point of the V?

 

 

 

 

I think making the reverse side shallower is probably the best way to go.  If I cut carefully it shouldn't hurt the strength of the return arm at the vee.  It's 1/8" steel, about 1/2" from the bottom of the vee to the edge.

[kpinnc 11,471]

9 hours ago, wallfish said:

See what I mean? I just realized I have no idea what Don says!

 

Agreed- but I'm in no way poking at Don. Rather I'm joking at myself, because he operates on a completely different level than me.

[Bill D 1,827]

Well I think it's done.  Going to try mowing with it this week then I'll break it down and paint it at some point.  I widened the vee in return arm about 3/8" at the opening by cutting the reverse slope on the return arm.  This made for a more gentle angle on the reverse slope.  Seems to have evened out the pedal pressure and total deflection of the return arm from forward to reverse.  

 

One minor detail I'd ike to mention for anyone thinking of copying my design; there is a nylock nut on the pivot bolt inside the hood stand (fun to install ).  This effectively double nuts the pivot bolt to prevent it from loosening in the hood stand

 

The best part about this design is that it required no drilling or cutting to install.  Just thread the prepunched hole in the hood stand for the pivot bolt.  

Edited September 27, 2023 by Bill D

[kpinnc 11,471]

12 hours ago, Bill D said:

Well I think it's done. 

 

Outstanding work Bill! 

[Bill D 1,827]

7 minutes ago, kpinnc said:

 

Outstanding work Bill! 

Thanks Kevin.  You're welcome to copy my design if you want.  The bearing is a sliding door roller from the local hardware store. I estimate the total cost of materials to be under $50.

[Handy Don 11,861]

12 hours ago, Bill D said:

Well I think it's done. 

Congrats, Bill, on a well-planned and executed enhancement. Looking forward to hearing your assessment of its performance during real work!

 

[Bill D 1,827]

6 hours ago, Handy Don said:

Congrats, Bill, on a well-planned and executed enhancement. Looking forward to hearing your assessment of its performance during real work!

 

Thanks Don.  I haven't mowed with it yet, but based on my test drive around the yard, the pedal pressure for reverse is perfect now.  I'm looking forward to seeing how my foot feels after using it to mow.  Not sure I'll be mowing this week.  My yard is a swamp from all the rain.

Edited September 27, 2023 by Bill D

[johnnymag3 2,508]

I am also curious, Bill.  As you know, I have a garage full of autos.    

[Handy Don 11,861]

7 minutes ago, Bill D said:

... based on my test drive around the yard, the pedal pressure for reverse is perfect now.  I'm looking forward to seeing how my foot feels after using it to mow.  ...

Having to apply continuous pressure when not frequently changing direction is a great reason to keep the “centering” pressure to the minimum needed to do the job well. I suspect this is why some makers created a “cruise control” -- an electromagnet that held the linkage at whatever place you set it. 

 

[Bill D 1,827]

1 hour ago, johnnymag3 said:

I am also curious, Bill.  As you know, I have a garage full of autos.    

Come over and test drive it.

[Bill D 1,827]

1 hour ago, Handy Don said:

Having to apply continuous pressure when not frequently changing direction is a great reason to keep the “centering” pressure to the minimum needed to do the job well. I suspect this is why some makers created a “cruise control” -- an electromagnet that held the linkage at whatever place you set it. 

 

My yard is small enough that I wouldn't have much use for cruise control.

[johnnymag3 2,508]

1 hour ago, Bill D said:

My yard is small enough that I wouldn't have much use for cruise control.

Don’t let him fool you. He’s got a massive yard and owns a nice piece of property in prime location.

Edited September 27, 2023 by johnnymag3

[Bill D 1,827]

21 minutes ago, johnnymag3 said:

Don’t let him fool you. He’s got a massive yard and owns a nice piece of property in prime location.

I've been to your house.  I'll trade you.

 

I do change directions a lot when mowing.

Edited September 28, 2023 by Bill D

[Damien Walker 241]

On 9/24/2023 at 2:45 AM, Bill D said:

What's your opinion @Damien Walker?

Hi Bill, sorry for the slow response, I've not been on the site for a while!

 

You have created a good solution I think, well engineered too and you appear to be heading in the right direction. 

 

To sort of summarise then, I agree with Don, the early-in-the-thread issues with the difference in pedal pressure going forwards and backwards were primarily caused by leverage, but also by geometry. To make the pedal pressure is the same in both directions, your notched return lever must be perpendicular to the pedal crank so that the geometry of the notch is the same in both directions and, you need to find a way of making the spring tension the same in both directions (ie Don's leverage issue). If you think about it, my coil spring system provides equal force in both directions by default (which is why I chose it!)

 

It's good to see that your pushrod clears the fan gear...clearly your pedal crank is longer than mine, but that will translate into shorter pedal travel. This doesn't matter two hoots if the machine drives well.

 

The two return lever idea would work, (provided you can arrange equivalent return springs) but it increases the complexity, so I think the thoughts about the shape of the notch may be the answer you are looking for. A steep angle and long arm should be equivalent to a shallow angle and a short arm. You could calculate the leverage ratio either side of the notch and try to do something similar with the angles of the notch. To try to explain this another way: if the distance from the pivot to the rear of the rear slope is half that of the distance between the pivot and the front of the front slope, you could try halving the slope of the rear half of the notch to make it half as difficult for the roller to climb the slope. (Phew that's a bit of a mouthful!)

 

I know what I'm trying to explain here but I'm not sure I'm being successful!

 

Keep going, I am confident your solution is a good one....and you haven't chopped the belt guard bracket off as I did!

 

[Damien Walker 241]

Moving the return lever pivot point up or down so that the lever is not perpendicular in the neutral position would have the same effect as changing the angles of the notch of course...

[Bill D 1,827]

Update:  I used it to mow this weekend.  Over all I like it.  Still trying to decide if I like the rocker style pedal I built for my GT1800 better or this one.  I see advantages to both.