Tub Grinders and Hay Grinders

A grinder turns coarse hay, straw and stalks into something stock can eat or you can bed with. It is also one of the most dangerous machines on a farm if you get careless around it.

Key points

Match the grinder to your tractor and your loader before you buy.
Inspect bales for wire, rocks and wrap before grinding.
Treat the rotor as live until it has fully stopped and the tractor is locked out.
Wear hearing and breathing protection every time.
Small herds rarely recover the cost of owning a grinder, so consider custom grinding.

What is the difference between a tub grinder and a hay grinder?

A tub grinder has a large rotating tub that carries whole bales or loose material to a hammermill at the bottom. A smaller hay grinder, sometimes called a bale processor with a grinding head or a horizontal grinder, feeds material in from the side or through a hopper. The tub style swallows round bales quickly. The smaller styles take more handling but need less tractor and less space.

Both rely on a spinning rotor with hammers or knives and a screen that sets how fine the finished product comes out. Most are driven by a tractor PTO, and a few have their own engine. Check your operator's manual for the PTO speed and power the machine expects, because running a grinder with too little tractor makes it plug and stall.

Who actually needs a grinder on the farm?

A cattle ranch feeding poor-quality round bales through a hard winter can stretch rough forage by grinding it and mixing it with supplement. A 30-acre hay producer with a weathered stack might use one to salvage bales that are too rough to sell. A hobby farm with six head and a few round bales a year almost never pays back the cost of owning one.

What should you ask before buying a tub grinder?

Most buyers focus on capacity and forget the supporting work. A grinder needs a loader that can lift a full bale to the tub, a level pad, and a tractor sized for the job. Ask the seller or dealer to show you the machine running if possible, and walk around it with the guards in place.

What tractor power and PTO speed does the manufacturer specify?
How are hammers, knives and screens replaced, and how available are parts?
Is there a clutch or shear protection on the driveline, and is it working?
Does the machine have a full set of shields, decals and a manual?
How much dust does it throw, and where will the exhaust of material land?

How do you set up a grinding site safely?

Choose firm, level ground away from barns, fences and power lines, and think about wind. Dust and chaff blow downwind, and so can thrown debris. Keep every bystander, child and pet well outside the work area, and never let anyone stand near the discharge.

A grinder can throw a stone, a piece of wire or a tramp metal fragment with force. Inspect bales for baling wire, net wrap remnants, rocks and dead animals before they go in. Remove twine and net wrap as the manual directs, since wrap wound around a rotor causes breakdowns and fires.

What are the biggest dangers around a grinder?

The rotor keeps spinning after the PTO is disengaged, sometimes for minutes. Never reach into the tub, hopper or discharge until the tractor is shut off, the key is out, the PTO is stopped and the rotor has come to a complete stop. Follow the lockout steps in the manufacturer's manual.

Hearing damage and dust inhalation are the quieter hazards. Wear hearing protection and a respirator rated for the dust the manual or your extension office recommends. Moldy hay can carry spores that cause serious lung illness, so treat dusty, old forage with respect.

Never bypass or remove a shield, guard or interlock.
Keep clothing, hair and gloves clear of the PTO shaft.
Keep a fire extinguisher at the site, since dry material and friction can ignite.
Shut down before clearing any plug.

How do you keep a grinder working season after season?

Hammers and screens wear, and a worn set gives uneven particle size and slow output. Inspect them on the schedule in the manual, grease the bearings and driveline as directed, and look for cracks in the tub frame and floor. Clean out stored material after each use so moisture and rodents do not move in.

If the rotor is out of balance, you will feel vibration that rattles the whole tractor. Stop and find the cause rather than working through it. Rotor balancing and bearing replacement are shop jobs unless you have the tools and training.

When to get help: Call the dealer service department or a qualified mechanic for rotor balancing, bearing and driveline repairs. Ask your local extension office about feeding ground forage safely, and your insurance agent whether the grinder and its site are covered.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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