7 Supplies for Brush Hog and Field Mower Maintenance

That jarring bang and shudder tells you everything you need to know: you’ve hit something solid, again. Whether it’s a hidden stump or a half-buried rock, a brush hog takes a beating that lawn mowers can only dream of. Keeping that essential machine running strong isn’t about luck; it’s about having the right maintenance supplies on hand before you need them.

Disclosure: As an Amazon Associate, this site earns from qualifying purchases. Thank you!

Why Mower Maintenance Matters for Your Fields

A well-maintained brush hog or field mower does more than just survive the season—it actively improves your land management. Sharp, balanced blades deliver a clean cut, which helps pasture grasses recover faster and suppresses the ragged, torn regrowth of invasive weeds. A properly lubricated gearbox and driveline transfer power efficiently, saving fuel and reducing wear and tear on your tractor.

Neglecting maintenance has a cascading effect. A dull blade forces the engine to work harder, while an unbalanced one sends destructive vibrations through the entire machine, leading to premature bearing failure and cracked welds. Regular upkeep isn’t just about preventing a catastrophic breakdown in the middle of a job; it’s a fundamental part of stewarding your equipment and your property effectively.

Safety First: Essential Personal Protective Gear

Before a single bolt is turned, safety is the priority. Working on heavy, sharp implements demands respect. Start with impact-rated safety glasses—not sunglasses. An angle grinder sends a shower of hot sparks, and cleaning the underside of a deck can dislodge dirt and metal fragments.

A pair of heavy-duty mechanic’s gloves is non-negotiable. They protect your hands from grease, sharp metal edges on the blades, and busted knuckles when a wrench inevitably slips. Finally, always wear steel-toed boots. A mower deck can shift unexpectedly, and a blade can be far heavier than it looks. This basic gear is the first and most important investment in any maintenance task.

Grease Gun – Lincoln 1134 Pistol Grip Grease Gun

Grease is the lifeblood of your mower’s moving parts, from the PTO shaft U-joints to the tail wheel pivot. A grease gun’s job is to force lubricant into tight fittings, pushing out old, contaminated grease and moisture. Doing this regularly prevents grinding metal-on-metal wear that quickly destroys expensive components.

The Lincoln 1134 Pistol Grip Grease Gun is the right tool for the job on a small farm. Its single-hand, pistol-grip design is a huge advantage when you’re reaching for an awkward zerk fitting underneath the deck. The build is solid steel, not cheap plastic, and it develops enough pressure (up to 7,500 PSI) to clear stubborn fittings. It’s a durable, no-nonsense tool that will last for decades.

Before buying, know that you’ll also need cartridges of multi-purpose lithium grease (check your mower’s manual for specific recommendations). Loading a grease gun can be messy the first few times, but the Lincoln’s design minimizes the hassle. This gun is perfect for the farmer who needs a reliable tool for regular maintenance but doesn’t need a battery-powered or pneumatic model designed for a commercial shop.

Gear Oil – Valvoline High Performance 80W-90 Oil

The gearbox is the heart of your brush hog, translating the PTO’s high-speed rotation into the immense, stump-busting torque needed to spin the blades. The gear oil inside is the only thing preventing those gears from tearing themselves apart. It lubricates, cools, and carries away microscopic metal particles.

For this high-stress environment, Valvoline High Performance 80W-90 Gear Oil is a dependable, widely available choice. It contains extreme pressure additives that form a protective film on gear teeth, preventing scoring and wear under the heavy shock loads a brush hog experiences. Its thermal stability ensures it won’t break down even after hours of cutting in the summer heat.

Always consult your mower’s manual for the exact oil weight and type specified. Using the wrong fluid can be just as bad as running it low. Checking the oil level is simple—usually via a plug on the side of the gearbox—and should be done before each use. For the hobby farmer, a one-gallon jug is a cost-effective purchase that will cover several oil changes.

Blade Sharpener – DEWALT 4.5-Inch Angle Grinder

Dull blades don’t cut; they tear and bludgeon. This not only leaves a ragged-looking field but also puts a massive strain on your mower and tractor. A handheld angle grinder is the fastest and most effective way to put a sharp, working edge back on a heavy brush hog blade.

The DEWALT 4.5-Inch Angle Grinder (DWE402) provides the perfect balance of power and control for this task. It has enough torque to remove metal quickly with a 60-grit flap disc, but it’s small enough to handle without fatigue. Its paddle switch is a key safety feature, shutting the tool off the moment you let go. The tool-free guard adjustment makes it easy to direct sparks away from your body.

There is a learning curve here. You must secure the blade in a sturdy bench vise before you begin. The goal is to follow the blade’s existing angle, working smoothly from the inside to the outside edge. This tool is for someone comfortable with power tools who understands the importance of safety glasses and gloves. For those willing to learn, it’s a versatile shop tool that pays for itself quickly.

Blade Balancer – Oregon 42-100 Magnetic Balancer

Sharpening a blade is only half the job. Grinding removes metal, and if you remove more from one side than the other, the blade becomes unbalanced. A spinning, unbalanced blade acts like an out-of-balance tire, creating violent vibrations that will destroy spindles, bearings, and seals in short order.

The Oregon 42-100 Magnetic Balancer is a simple, foolproof tool that prevents this costly damage. It’s a cone-shaped, multi-level balancer with a strong magnet at its peak. You simply place the center hole of the blade on the cone, and the heavier end will dip down. It instantly shows you which side needs more metal removed.

This is not an optional step. After a few passes with the grinder, place the blade on the balancer. Note the heavy side, and grind a little more material from that side’s cutting edge. Repeat the process until the blade sits perfectly level. This balancer is for everyone who sharpens their own blades. It’s a tiny investment that protects the several-thousand-dollar investment of your mower and gearbox.

Wrench Set – GEARWRENCH 3/4" Drive Socket Set

The bolts holding your brush hog blades on are massive for a reason, and they are often seized with rust and dirt. A standard 1/2" drive socket set from a home mechanic’s kit often lacks the leverage and strength to break them loose. Attempting to do so with the wrong tools can result in stripped bolts and bloody knuckles.

This is where a GEARWRENCH 3/4" Drive Socket Set becomes essential. The larger drive size, thicker socket walls, and long breaker bar provide the immense torque needed to safely loosen and tighten blade bolts and other large fasteners on farm equipment. The 6-point socket design grips the bolt head securely, dramatically reducing the risk of rounding it off.

This is a serious tool for serious work. It’s an investment, but it’s the correct one for the scale of the job. Before buying, check the nut size on your mower’s blade bolts to ensure the set includes the correct socket. This set isn’t for daily tinkering; it’s for the heavy-duty maintenance tasks that define the difference between a well-maintained machine and a neglected one.

Shear Bolts – Grade 2 Shear Bolt Assortment Kit

A shear bolt is the cheapest and most important part on your entire mower. It connects the PTO shaft to the mower’s input shaft and is designed to be the weakest link in the system. When you hit a rock, the shear bolt snaps, disconnecting the tractor’s power from the gearbox and preventing a catastrophic, multi-thousand-dollar failure.

Using the wrong bolt is a critical mistake. Never replace a shear bolt with a standard, high-strength bolt. A Grade 2 Shear Bolt Assortment Kit is what you need. Grade 2 bolts are soft and designed to shear under a specific load. A harder Grade 5 or Grade 8 bolt will not break, transferring the entire shock load directly into your gearbox and likely shattering the gears.

Keep a handful of the correct size shear bolts, along with the necessary wrenches, in a toolbox on the tractor at all times. They are a consumable item, and having them on hand can turn a day-ending event into a five-minute field repair. This kit is an absolute necessity for every single brush hog owner, without exception.

Degreaser – Simple Green Pro HD Heavy-Duty Cleaner

Grass, dirt, and grease build up on a mower deck, trapping moisture and accelerating rust. A thick layer of grime can also hide cracks in welds or leaking gearbox seals. A powerful degreaser is essential for cleaning the machine thoroughly enough for proper inspection and maintenance.

Simple Green Pro HD Heavy-Duty Cleaner is an excellent choice for this job. Unlike harsh petroleum-based solvents, this professional-grade formula is biodegradable and non-corrosive, making it safe for painted surfaces, plastics, and rubber seals. It’s a concentrate, so a single gallon can be diluted to make many gallons of powerful cleaning solution, offering great value.

For best results, apply the diluted cleaner with a spray bottle, let it sit for a few minutes to break down the grime, then scrub with a stiff brush and rinse with a pressure washer or a strong jet from a hose. This cleaner is ideal for anyone who wants to keep their equipment in top shape, making inspections easier and extending the life of the machine.

Pro Tip: Torqueing Lug Nuts and Blade Bolts

Guessing at "tight enough" is a recipe for disaster. Both blade bolts and the tail wheel’s lug nuts have a specific torque value, listed in your mower’s manual. Under-tightening can allow a blade to come loose during operation—a terrifyingly dangerous scenario. Over-tightening can stretch the bolt’s threads, weakening it, or damage the hub or blade carrier.

The only way to get it right is with a torque wrench. After tightening bolts with your 3/4" drive set, use a torque wrench to apply the final, precise amount of force. It’s a critical step that ensures safety and mechanical integrity. Think of it as the professional finish to any maintenance job involving critical fasteners.

Building a Small, On-the-Go Field Repair Kit

A breakdown rarely happens conveniently next to the workshop. A small, dedicated field kit can save you a long walk and significant downtime. The goal isn’t to rebuild the mower, but to handle the most common issues that bring work to a halt.

Start with a small, weatherproof toolbox or ammo can. Inside, pack the essentials:

• Several spare shear bolts of the correct size and grade.
• The two wrenches needed to replace a shear bolt.
• A small tube of grease or a compact grease gun.
• A pair of pliers and a multi-bit screwdriver.
• A bundle of heavy-duty zip ties and a roll of electrical tape.
• A clean rag for wiping hands or checking fluid levels.

This simple kit, kept on the tractor, can be the difference between finishing a field and losing half a day to a minor problem. It’s proactive planning that pays off when you least expect it.

Post-Mowing Cleanup and Proper Storage Steps

The work isn’t over when the engine shuts off. A few minutes of post-mowing care dramatically extends the life of your equipment. The first step is to clean the deck. Use a leaf blower or compressed air to blow off all the dry grass and chaff from the top of the deck and around the gearbox. This prevents the buildup from holding moisture against the metal.

Next, conduct a quick visual inspection. Look for any new dents, cracks in the welds, or leaking seals around the gearbox and wheel hubs. Check the tire pressure on the tail wheel. If you’ve scraped any paint off, hitting the bare metal with a quick shot of implement paint will stop rust before it can start.

For storage, always keep the mower under a roof if possible, whether in a barn or under a lean-to. Lower the deck all the way to the ground or onto blocks to take pressure off the tractor’s hydraulic system. This simple routine ensures your mower is not only clean but ready and reliable for the next time you need it.

Proper maintenance transforms a brush hog from a simple, brute-force tool into a reliable partner in managing your property. These supplies aren’t expenses; they are investments in efficiency, safety, and the long-term health of your most valuable equipment. A little time in the workshop saves a lot of time, money, and frustration in the field.