OutdoorKing Repair Forum Forums Repairs and Maintenance Questions On Ride On Mowers Questions on Greenfield Ride On Mower Frames Greenfield Evolution Front Axle Beam

Hi folks,
I am attempting to repair a Greenfield Evolution which needs a fair bit of TLC, so I might be asking for your advice on several issues as time goes by.
It�s an Evolution 13-32 with the Honda engine.

My first problem is the front steering.
The Axle Beam (21) has a central Pivot Bolt (17), and two bolts welded through it (you can�t see them in the picture) opposite the washers marked (10).
The Axle Beam pivots through a Backing Plate which is bolted across the side rails at the front of the chassis, unlike other models where this plate forms part of the chassis itself.

The two side bolts move up and down in arced channels cut in the Backing Plate, and mine have nuts at the rear, although there are no nuts indicated in the parts list.
The bit I�m not understanding is that if I do up these nuts, it will bind the Axle Beam against the Backing Plate, and not allow the Beam to pivot properly.

Any suggestions?

I have looked up the 13-32 parts list and manual and haven't found that design, but I'll just work from the information you have posted. It appears to have a Ferguson-like pivoted front axle, which requires some way to limit the movement of the axle on the pivot. The easy way would seem to be to have a stop on the frame for the top of the axle to hit, but you could do it with a slotted guide such as your diagram shows. You then need a rod or bolt that is rigidly attached to the axle, and slides in the curved slots in the guide plate, with its travel limited by the ends of the slots. Normally that rod or bolt would be attached strongly to the axle, and would just have a pin-projection to slide in the guide. That means it would be a special part, not a bolt, and the part that projected through the guide would just be a smooth pin. Has someone lost or thrown away the special parts, and stuck in a couple of bolts, somewhere along the line?

Addendum: I've now found the parts list your main illustration above comes from (it's Illustration 5 in "Evolution 14-32.pdf") but I can't find your slotted plate. Can you give me a reference for that please? I hope it will also show these special parts.

Thanks, Grumpy.
You are correct in identifying the Axle Beam on my model as listed in Illustration 5 in "Evolution 14-32.pdf". Mine is the 13 HP Honda motor, therefore my model is a 13-32.
The illustration for the slotted plate, however, is not precise, but is from an Evo 2 Manual, since the aforementioned Manual doesn't show it very clearly (It is Part 32, GT6357 in the actual Manual. I just copied it from an Evo 2 model to illustrate the similar arrangement of the curved slots.)

For comparison, I have another Greenfield, an Evo 111, which has two threaded "pins" as you suggest, that are integral to that Axle Beam. On that Evo 111 Model, the Backing Plate is integral to the Chassis, and has a further "Backing Strip" behind that, through which the two pins pass. On mine they have nuts on the pin ends. For illustrative examples, see the following extracts from the pdf Manual for the Evolution 3 12-5HP 32-30. p.1 #15 is a "Backing Strip"; p.5 #20 shows an Axle Beam with two "pins"

Your suggestion that these pins serve only to limit the range of movement of the Axle Beam is a good one. I'm intending to attach nuts to the end of the Pins very loosely, and rely on Locktite to stop them falling off, although perhaps nuts aren't required at all. In any case the central pivot bolt stops the Axle falling off!

Many thanks

Your Evo 3 sounds like the design I had in mind. Is there enough thread to fit a locknut to retain that loose nut? It would be a neater solution than loctite.

I'm afraid there's not!
On the Evo 3, the nuts just snug up against the Backing Strip, which rotates up and down with the pins (i.e. The Backing Strip remains parallel with the Axle Beam while rotating). I guess in this case the nut against the backing Plate acts as a "locknut".

However on the Evo 13-32 that I'm working on, there are just the washers (#10 in my original pic), which I presume go between the Axle Beam and the Backing Plate, as does washer #16 which is on the Pivot Bolt.

In replacing the nuts (which were already on the pins), I decided to add flat washers behind the Backing Plate, to perform the same sliding function as the Evo 3 Backing Strip. Partly I did this because the arced grooves in the Backing Strip have been worn out of shape (presumably due to movement in the pivot bolt and bush at some time) and I didn't want the nuts to jam in these grooves. This leaves no room for a locknut, or even a spring washer.
I will look at whether there is room to leave these (new) washers off, and instead use nuts and lock-nuts, as you advise.
Cheers

There are at least two possibilities other than simple lock nuts. One is to buy a self-locking nut or a grub-screw locking nut. The other is to buy a pair of special lock nuts that are half as thick as standard nuts.

I'm not clear on the situation regarding the washers. You may need washers to enable the pins to slide smoothly in the slots. Lock washers on sliding parts are a no-no. Can you post pictures of this sliding mechanism?

I think I'll just use some Nylock nuts over flat washers. Unfortunately, I've put the Axle back on, so can't post pictures showing any detail. Cheers

I think Nyloc nuts will work so long as you don't keep removing or adjusting them. The plastic friction device doesn't last all that well if you keep moving them on the thread.

Hi ichiwowa, and a warm welcome to the forum. It's great to have you aboard. We all like to learn new things and tinker here.
Once again,

Thanks for the welcome, Deejay!

@Grumpy, in regards to your earlier idea that the Axle Beam may originally have had "just have a pin-projection to slide in the guide", in order to limit the rotational travel of the Axle Beam, I think the function of the nuts on those pins may be to limit the amount of "forward-and-backwards" movement of the front Axle Beam, caused by the push-pull action of the steering tie-rod. I notice when I turn the steering wheel from side to side while stationary, there is a fair amount of lateral force applied to that Axle Beam. Perhaps this also serves to protect excessive wear at the central Bush for the Pivot Bolt?

Meanwhile I have obtained another Evolution 14-32 for parts, and will take a look at its front axle for comparison when I get a chance.

Regards

ichiwowa, there has to be a way to locate the axle in the fore and aft direction, especially to cope with the backward force on a wheel when the tractor hits a bump. That could be done in various ways, but using the axle-tilt-limiters is a possible way as long as the slotted plate is rigid enough for the purpose. It would be best if the (slotted) support plate is behind the axle, since the wheel-bump load would nearly always be backwards. If the steering has a fore-and-aft drag link from the steering box on the bottom of the steering column, that also produces some fore and aft force on the end of the beam axle. I think as far as tie rod (i.e. lateral) steering forces are concerned, I'd rather make the central pivot of the beam axle big enough and strong enough to resist them unassisted. Multiple redundant restraints are seldom reliable because they each have different rigidities, and you never know quite how much load each of them is taking.

So, at this point I don't know if there is something else resting against the back of the axle to locate it along the tractor axis. If there is nothing else locating the axle, the slotted support plate has to do the job. However if that plate is behind the axle, it may not be necessary for the pins to have nuts on them: the axle is fairly strong in bending, so supporting both sides from behind should be sufficient.

Back in the days when cars had beam axles on the front, they used to have rather strong axial location measures, but the biggest forces they had to cope with were caused by the front brakes ("spiking" the brakes causes very large forces on the axle due to suddenly absorbing the rotational momentum of the wheels and tyres). However ride-on mowers seldom have front brakes, and besides that they have tiny wheels and tyres, and travel at very low speeds, so wheel and tyre momentum is not a factor.

My bad, Grumpy! When I said "the push-pull action of the steering tie-rod", I meant the Drag Link, not the tie-rod.

Between the Axle Beam and the Backing Plate are three washers. One for the Pivot Bolt, and one each for the side Bolts, or Pins,(which are welded into the Axle Beam. So you can look down through this slight gap made by the washers.
So when I turn the steering wheel from side to side while stationary, I can see this gap opening and closing a tad, if that makes any sense?
While the Axle Beam is certainly strong enough not to bend, I thought perhaps forces to it in the forward-backwards direction (if unrestrained by nuts on pins) might cause the Axle to exert excessive leverage on the central Pivot Bush and promote undue wear.
But I'm no engineer, just trying to understand the sucker!
Anyway, I really appreciate your input.
Cheers

ichiwowa, I'm not saying you shouldn't adjust the nuts to give a suitable, modest fore-and-aft clearance between the beam axle and the support plate. That will ease the load on the central pivot. You should check what the owners' manual says you should do about lubricating the slots in the support plate, and especially the central pivot.

I thought this forum was the (de-facto) Greenfield Owner's Manual!!! lol

The problem is that there are no happy answers when something has to be lubricated whilst exposed to dirt. Oil or grease traps the gritty dirt and forms a substance almost identical to valve grinding paste, so the metal gets worn away. On the other hand if you don't lubricate it the two dry metal surfaces can adhere to each other and tear ("spalling"). The proper answer is to use compatible metals and/or seal the joint so that no dirt can penetrate, and lubricant can be retained.

The answer usually is to try to do a bit of each. In particular, do not have mild steel rubbing against mild steel, or even worse, aluminium rubbing against aluminium. Mild steel against hardened steel is fairly good (it's wheelbarrow engineering, but good quality wheelbarrow engineering). Hardened steel against bronze is quite nice, and you can make it better by making the bronze part porous and soaking it in lubricant during manufacture. For those Greenfield front suspension joints, a good solution would be to use hardened steel pivots/pins (that is, high tensile bolts instead of soft bolts), a bronze bush in the center axle pivot bearing, and bronze washers rather than mild steel ones in all three front axle joints, then wipe grease sparingly on all of the parts regularly. Finally, don't work in dirty conditions that would get grit in the bearings, and wipe it off if it occasionally happens.

But having said all that, it is almost always best to follow the manufacturer's recommendations (not the local dealer's recommendations, unless they are the same).