Parallel arm rebuilding / exchange

One of the most important aspects of planter maintenance is how much overall slop is in the parallel arms on the row units. 

As this wears, this creates vibrations in the row unit as it’s running through the field. This will work against the performance of your downforce, closing system, disk opener depth, row cleaners, etc. Once you start to get at least 1/2″ of slop in your row unit when you lift up and down on it, we recommend rebuilding your arms.

Parallel arms on planters are an all-around poor design. 

Manufacturers use a bushing that rubs against the housing on the arms, with the idea that when they would wear, you would just replace the bushings. However, the bushings that they use are harder than the parallel arm housings themselves. Because of this, the bushing does not wear and the housing becomes the new wear point. This means that nearly every time we get into a planter rebuild job, we would end up replacing complete parallel arms. 

Solid Rock Ag has been on a mission to find a better solution for this problem and we have finally found a cost effective, simple, robust solution. We take regular parallel arms, have the holes milled out larger, and these hardened wear sleeves pressed in. Then we use a bushing that is a slightly softer than the race. Because of the material used, these rebuild kits have a much longer wear life than a traditional OEM arm, and when they do wear, the bushing is the main wear item as it should correctly be. They are also much simpler to install than some of the other systems out there that require drilling and reaming out holes in the arms, shanks, w-mounts, and parallel arms.

Because we actually CNC mill the holes out instead of using a reamer, we have complete control over the holes and are able to keep them within a very tight tolerance. This allows us to use a hardened press-fit sleeve bushing, as well as be sure we are taking a very minimal amount of material from areas that would reduce the strength of the arm.

We offer an exchange program where carry sets of powder coat painted and rebuilt arms which we will swap a grower out for the arms on his planter. Currently, the swap out is only available for Deere ME2 – ME5, and Kinze 3000 Row Units. If you are interested in another make or model, we likely can still rework them with this upgrade. We just cannot offer the swap-out program on them and will have to schedule them to be either dropped off or shipped to us. If this is something you are interested in, give us a call so we can verify availability.

Wear Life: So far, one planter has over 1000 acres per row with still very few noticeable signs of wear. We are very optimistic about the wear life on this kit. As of now, we have not yet had a single customer need to replace a single bushing due to wear. However, when it does eventually wear, because of the bushing design it should be only the bushing at first that needs to be replaced. In theory the sleeves will also wear eventually, however these are also replaceable. So as with our solution, you should never have to replace your arms again.

The refurbishing process

1. We take used arms and send them to a paint shop that burns the old paint off, sandblasts, and then powder coats them.
2. Those painted arms come back to our shop where we have a CNC Milling machine that we use to mill out the pivot holes. This step brings the center-to-center distance between holes back to the factory dimension, removes the worn material, and gives us the precision hole needed for pressing the sleeves.
3. The hardened sleeves are pressed into the arms using an arbor press. They have an interference fit measuring +-0.0014 against the milled hole.
4. Alignment is checked with a high precision bar to pass through both holes in the lowers (See pictures below). Aligned sleeves provide better wear resistance since there is more surface area to rub against. The arms are now finished and ready to be packed along with the bushings required and then be shipped out.

The exchange program

The normal process steps

1. An agreement is reached between Solid Rock Ag and the customer in regards to per row cost to the customer, qty of rows, shipping costs, and the amount Solid Rock Ag will refund per row, etc. Typically the customer will pay for shipping out, and Solid Rock will pay for shipping back the used arms.
2. Refurbished arms are shipped to the customer
3. The customer installs components row by row swapping out for the refurbished arms.
4. The customer ships old rows back to Solid Rock Ag
5. When Solid Rock Ag gets the old arms back a payment is sent to the customer for the number of rows we are able to refurbish times the amount agreed upon at the beginning.

This is not the only way this can be done. We can also refurbish your used arms and not send them through the painting process but this requires more scheduling effort as there is a great deal of setup to switch between arm styles. Reach out if you are interested in this.

Other Notes: We are able to refurbish almost all arms. Some of the Deere lowers get abnormal wear which creates a challenge and about 1 in 10 we are unable to recover on average. Some planters are worse than others. Thin arms or arms with abnormal wear create another challenge as we may not be able to recover them due to how thin they get by the time we mill the holes.

FAQs

Q: What material are the sleeves and bushings made from?

A: A machinable grade of carbon alloy steel that is hardened and given a protective coating in order to protect against corrosion. That is what gives them the gold or brass appearance. 

Q: How long have you been doing this?

A: We have been doing this since 2019. Originally we worked with a machine shop and eventually brought the entire process in house.

Q: Does hardware come with it?

A: We do not supply other mounting hardware at this time. If the bolts are kept tight, the wear surface should only actually be on the bushings themselves. If hardware needs replaced, we recommend sourcing them locally.

Q: Are bushings the same as OEM?

A: No. The bushings we supply are custom made and much more hardened and in some cases significantly heavier duty than OEM. See Kinze bushings for an example in the gallery below.

Q: What is the recommendation for when to replace worn parallel arms?

The general rule of thumb is to replace the arms when there is 1/2” or more play when you lift up and down on the row unit. if someone is using an Automatic Hydraulic Downforce system, I generally recommend replacing them a little quicker since these systems are using a load cell to control with which. and the more vibrations that the row unit has, this will diminish the performance of the downforce system.

Q: Do you offer a kit of bushings and sleeves so I can refurbish the parallel arms myself?

A: We do not currently offer this as an option.