The blade spindles on a lawn mower turn about 3000 times per minute. During this operation, the moving parts create a lot of friction that, in turn, creates a great amount of heat. So to prevent the friction from causing excessive wear and potential seizing, manufacturers use grease as a lubricant inside the spindles.
In addition, manufacturers like John Deer recommend adding grease to the spindle after every 25 hours of use to prevent such problems. That all sounds fine, but how do you add grease to a spindle? Let’s take a look.
Greasing Lawn Mower Spindles (The Short Explanation)
To grease a lawn mower spindle, you need to inject a suitable grease into the spindle via the attached hydraulic grease fitting. Here are the steps you will need to follow.
- Locate the hydraulic grease fitting
- Clean the hydraulic grease fitting
- Fill the grease gun with suitable grease
- Connect the grease gun to the hydraulic grease fitting
- Inject the grease into the spindle
- Disconnect the grease gun
- Clean the hydraulic grease fitting
Why It’s Important to Periodically Grease Your Lawn Mower Spindles
As I mentioned, a lawn mower spindle can generate a lot of friction and heat during operation, especially when the lawn mower works for long periods at full speed. As grease is used, it starts to break down and burn off. Over time, there is less and less grease left in the spindle, which is why it’s a good idea to grease mower deck spindles.
So, the less grease or lubrication available, the harder the spindle and the lawn mower have to work. Therefore not only will the spindle suffer, but so will your lawn mower. Parts that can be affected are the spindle mounts, the deck belt, the clutch, and the engine itself.
Here are just a few problems you might run into and some extra repairs you might need to do if you don’t keep on top of greasing mower spindles.
Best Grease for Lawn Mower Spindles + Other Equipment You’ll Need
Grease comes in a variety of different grades for different applications. Some are designed for light use, and some are specially designed for heavy high-pressure use. I use a general-purpose grade 2 grease suitable for lawn mower spindles. There really is no need to use high-grade greases as these are designed for different applications. After all, we’re talking about lawn mowers and not combine harvesters.
So the easiest way to find the right grease is to head down to your local lawn mower shop and see what they have available. They’ll more than likely have the best grease for lawn mower spindles.
Along with the grease, you will need a grease gun to inject into the lawn mower spindle. There are two things you need to make sure match up with the grease and your lawn mower. The first is the size of the tube of grease. Lawn mower spindle grease comes in a variety of different size tubes, so you’ll need a gun to match. I recommend asking for a standard-size tube, not the big one or the little one.
Then you can get yourself a standard grease gun. Next, you’ll need to make sure that the grease fitting on your lawn mower spindle matches that of the gun. Usually, the fitting is a standard-size Zerk fitting. So, double-check the grease fitting size in your manual or ask one of the people at your local lawn mower shop. But I’m 99% sure it will be the standard Zerk fitting.
How to Grease Lawn Mower Spindles (Step By Step)
Now that you have your new tube of grease and grease gun, let’s go over how to grease a lawn mower spindle. Here are all the steps you’ll need to follow to keep your spindles running smoothly.
Locate the Hydraulic Grease Fitting
The first step is to locate all the grease fittings on your lawn mower. Usually, a diagram on your lawn mower will show you where all the fittings are. You might find this diagram under the hood of a tractor mower or under the footplate on a zero-turn lawn mower. Failing this, take a look at your owner’s service manual.
Also, you might find a few other spindles or bearings that use the same method, which you can service at the same time. For example, I know the wheels on my lawn mower also have zerk grease fittings, so I do these at the same time as my deck spindle.
Clean the Hydraulic Grease Fitting
Once you have located all the grease fittings, you’ll want to clean them and remove any dirt and grass clippings that might be attached. This is because whatever is attached to the end of the grease fitting will be injected into the spindle. Stuff like dirt and sand definitely won’t help the bearings. So, grab an old rag and give the fittings a good cleaning.
Fill the Grease Gun with Suitable Grease
I had some trouble the first time it tried to fill a grease gun with grease. I thought it would be just the same as a caulking gun from the decorating section at the hardware store. Nope, not quite. Here’s a quick overview of how to load grease into a standard grease gun.
- Pull the Plunger and Twist it to Lock it into Place
- Unscrew the Cylinder
- Remove the Plastic Cap from the New Tube of Grease
- Insert the Tube of Grease into the Grease Gun Cylinder
- Remove the Metal Cap from the Tube of Grease by Pulling the Ring Pull
- Reattach the Head Assembly to the Grease Gun Cylinder
- Release the Plunger and Push it Back into the Cylinder
- Pull the Grease Gun Trigger Repeatedly to Prime the Gun
- Stop Priming when Grease Starts to Come Out of the Nozzle
Connect the Grease Gun to the Hydraulic Grease Fitting/Zerks
With your loaded grease gun, press the end of the grease gun’s hose with the zerk connector onto the fitting attached to the spindle. There is usually a clip inside the nozzle that will snap onto the zerk fitting. So, make sure you give the nozzle a good push so that it firmly clips into place. If you don’t, then you’ll end up with grease squirting everywhere.
Inject the Grease into the Spindle
The next step is to inject the grease into the spindle. Usually, spindles are not 100% sealed, which means that when you overfill the spindle, grease will seep out of the gaps between the bearing housing and the spindle.
So, pull the trigger of the gun until you start to see grease seep out of the gaps in the spindle or back out of the nozzle of the gun. Just be careful that you have the nozzle correctly attached because you might think the spindle is full when it’s actually not.
Disconnect the Grease Gun
You can remove the nozzle when you think you have the lawn mower spindle full of grease. A firm pull should be enough to disconnect your gun from the lawn mower grease fitting.
Clean the Hydraulic Grease Fitting
Finally, use a rag to clean up any excess grease from the spindle and move on to the next spindle.
How Often Should You Grease Your Lawn Mower’s Spindles?
As I mentioned before, John Deere recommends that you grease your lawn mower deck spindles every 25 hours. However, they also say you need to grease a new spindle after 8 hours of use. So if you have a new lawn mower or have just replaced a spindle, make sure you add new grease once the spindle has had a chance to set in.
Now for me, I grease my spindle more often than what my manual states. This is because I know it’s much easier to pull out my grease gun than it is to replace a spindle, and it’s definitely a lot cheaper. So, check in your manual and see what your manufacturer recommends, then knock off a few hours.
For example, my manual states my lawn mower spindle should be greased every 25h, so I do it every 20h. I always think it’s better to be safe than sorry.
Do All Lawn Mower Spindles Need to be Greased?
If you find the phrase “non-serviceable” in your manual, then there is no need to add grease, and you’re not going to find a grease fitting. So it doesn’t matter if you have the best grease for lawn mower spindles since you will not be able to use it.
The best thing to do is check the grease fitting diagram for the location of all the fittings and service all the ones that can be serviced.
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