Another Hydro foot pedal conversion - 518H

[Bill D 1,922]

2 hours ago, Damien Walker said:

Hi Bill, the crank simply gets in the way of belt guard mounting tab....here's a spare guard showing the problem:

 

Conceivably then, you could change the angle of the crank w.r.t. the pedal, but my guess is that the crank would have to lean backwards quite steeply which would worsen the pushrod approach angle and probably limit the pedal travel. I am unfortunately long past the stage of brazing the crank on so I can't experiment for you, but there may be mileage in your suggestion. I can try to add the belt guard mount into my model and see what that does to everything else.... I admire your wish to keep things as standard as possible, that is usually my mantra too but I was beyond the point of no return for this one when I found out and actually think the bent metal strip that masquerades as a guard mounting is a bit rubbish (I've had them crack off before now) so as mentioned, my solution to my non-recoverable situation was to involve the decisive use of my angle grinder! I can vouch for my non-standard guard mounting solution though...it's far better than the original (honest!).

 

Yes, Matt's return spring solution will surely work well and it only requires one spring (doesn't work for me due to power steering pipes) but it occurs to me that you could mount my compression spring system at the rear end of the pushrod....this would be reasonably accessible under centre cover plate. Marking the mounting holes for the fork would be much much easier than where I suggested in my drawing.

 

As for those ghastly metric dimensions, I am old enough to understand the imperial system well and in some ways prefer it - you Americans aren't that crazy really! When it comes to engineering though, they are now a bit of a nightmare over here because imperial sized stuff is either not easily available or expensive and our dear government probably made it illegal to sell imperial sized Rose joints anyway (they DID make it illegal to sell bananas  in pounds rather than kilograms). Decimal inches is probably the way to go, but the imperial screw sizes are a bit hopeless: 1/4" - 28 makes a lot of sense, but what the heck is a #12-28 from the same series! I see Lee has ticked you off for asking (thanks Lee, much appreciated ) but assuming we can stabilise what I am drawing, it may be that the CAD system will do it for us.....the only problem is that you won't get useful sizes. 10mm for example is 0.394" which is a tad larger than 3/8"! What I really should have done is accepted that Wheelhorses are imperial tractors and designed in imperial.....and then struggled to buy joints and fasteners for months. As it happens, when I came to use the left hand 1/4-28 Heim joints, I found they had shipped 6mm instead  I blame Napoleon!

 

An earlier incarnation of my drawing for manual tractors still had a horizontal pushrod but elevated somewhat with the difference in height from the pushrod to the crank being taken up by a right angle bend in the pushrod. I decided that wasn't so good and came up with the version I presented above. Now that we're talking about belt guards though, may be my original idea was not so bad after all. 

 

Let me see what I can do with the CAD...it's quite intoxicating when you get into it and the practice is good for me. I learned how to draw a spring for this exercise for starters!)

 

Finally, conversion to imperial is dead easy with a calculator....simply divide the mm by 25.4 and you have inches (but I guess you already know that 😉)

 

 

Thanks for the information.  I didn't know conversion from metric to imperial was that easy. Math has never been my strong point.  As for sourcing materials I understand the value of using what you can get easily.  My apologies if you were offended in any way.  Bill

[Damien Walker 246]

Ok. let's see if this works:

The Belt Guard  Bracket is shown in Wheelhorse Red...I hope it is accurate.

 

 

There's approximately 1" (25mm) of vertical travel in the front Heim joint in this configuration...which will hopefully be accommodated by the slot in the fork. I'm not sure how much vertical movement there is in my original build that's on the tractor (it's now gone midnight so I'm not going out there to look tonight!). I'm also not sure how much fore/aft travel is required...it's a while since I measured that. Obviously the best crank configuration for fore/aft movement would be with the crank vertical in the neutral position. Clearly it's not vital as my original set up works fine

 

The elbow on the front pushrod also looks rather alarming but I think it would be reasonably well supported by the two Heim joints and the spring and slot arrangement (ie I don't think it would 'flop about' as the pedal moves).

 

Chop  that bracket off Bill, I dares you!

 

(No offence even perceived, let alone taken about metric to imperial conversions Bill, though I did have a major issue some years back when working in the aerospace industry over this. I worked for a British company that had acquired an American organisation with a similar portfolio. During the merger, it was decided that we would adopt the US drawing standard. Unfortunately 'those crazy Americans', didn't appreciate that with a ratio of approx. 25:1 between the two standards, you couldn't apply the same tolerance system (ie the size of the allowable error) to both. Applied wrongly in one direction, things become very loose and if applied in the other direction, they are impossible to manufacture! My attempts to improve the standard drawing template were not well received on the other side of the pond. 'We have been using that template for years, how can you spot something like that?' I think was the retort! Names had best remain anonymous but what I would say is that two offices working remotely is very much to be avoided, regardless of the nationalities!)

[Damien Walker 246]

And bingo, as if by magic, here are some imperial dimensions (at the touch of a button). As mentioned, the sizes are a bit awkward so you could round up or down a bit to the nearest sensible imperial sizes. At 4.291", the overall length could easily be 4.3" (or 4 5/16" (4.3125"))

 

The only really important dimension for the crank is the 1.26"...that was a tight fit on the crank casting. All the others are only related to neatness and pedal travel.

 

 

This one is easy as none of the dimensions are vital. I suggest: 3" hole spacing and 1" wide 'arms'. Need to be slightly careful of the 1.417" dimension....that has to fit neatly onto the flange on the pedal...I haven't measured it but 1.5" would surely fit?. I mounted the toe bracket using countersunk socket cap screws btw. The pedal rod is 4" long if I recall...but again, precision is not vital.

 

Overall length of the centres Heim joint to Heim joint on my version, is 17.5" (not including bends or right angles).

 

I thought I had recorded the springs I used but I can't find it on the thread: 70mm long, 12.5mm O.D. 1.7mm wire. When assembled they are pretensioned to 57mm...which  translates to: 2.75" long 1/2" O.D. and 0.067" Wire pretensioned to 2.25".

 

Let me know of you need more detail (e,g. return spring section, pushrods etc)

[Damien Walker 246]

Dear All, after mulling over the manual steering space issues, here are my current thoughts...for what they are worth!

 

1) My original design won't fit manual steering tractors (oops!)

2) After looking at my C175, it is clear that the engine mountings will restrict the travel on  my Wheelhorse-Brake-pedal-with-added-crank design

3) If we're going to have a pedal pivoted on the front foot plate mounting rod, then I think that compromises the belt guard front lower mounting tab. I think it is better to create a sound pedal design than worry about this tab, I like the Wheelhorse Brake pedal system and so I am happy to cut the tab off and provide a different mounting elsewhere (sorry Bill!).

4) Space inside the centre console is restricted...there is a plate with a large grommet in front of the control yoke that makes access particularly difficult. There's probably more than enough room for the pushrod system but it is getting in there to fit it all that is difficult.

5) Flag gear gets in the way of the pushrod for a nominally straight run and leaves little room for the 'coil over pushrod' return spring arrangement near to the pedal (especially if the crank is brazed on at the 10 o'clock position to allow the belt guard to be retained.

 

So..... I have been looking at fitting the pushrod outside of the centre console but inside the belt guard:

 

Here's the current idea:

 

 

This has the disadvantage of needing a slot cutting in the side of the console to get to the control yoke, but it doesn't have to be a precision curved slot as I have drawn...it just needs to be big enough to allow adequate movement (approx +/- 1" of travel). I did consider using the control yoke spindle as an axle and operate it by fitting a crank outboard of the console, but the belt tensioner is really too close. The practicalities of fitting a pushrod here remain to be tested....there's about 1" of clearance between the console and the drive belt so there should be enough room. The particular advantage of this is accessibility and the fact that the lower Heim joint doesn't interfere with the C175 engine mountings.

 

I have considered Matt's pushrod and the existing brake rod slot in the console, but Matt uses an underslung crank which may interfere with the tiller drive....I also admit to laziness here, I don't want to be bothered dismantling the tractor as much as you have to for Matt's installation (and I can't uses his return spring system due to power steering pipes!).

 

If I can get it all to fit, this latest incarnation only requires the removal of the belt guard and footplate, a slot for the link to the control yoke and and the return spring fork mountings to install....and of course it requires the crank brazing onto the pedal shank. The exact shape of the pushrod and the position on the fork mounting would be determined by experiment.

 

Any thoughts (particularly on how to go about cutting the slot!)?