Rotary Cutter Blade Pan (Stump-Jumper) for 40hp Box

What It Is

The Rotary Cutter Blade Pan (often called a stump-jumper) is the heavy-duty steel disc that mounts directly to the gearbox output shaft on a 40hp-class rotary cutter. It provides a reinforced mounting surface for the blades and protects the gearbox from impact when you hit stumps, rocks, or other debris.

Fitment & Compatibility

Before buying, confirm these three things:

• Deck size & brand: This pan is designed for Rotary brand cutters (40hp gearbox rating) and will not fit most other brands without modification. Check your cutter’s model number against Rotary’s compatibility list.
• Shaft size & bolt pattern: Measure the gearbox output shaft diameter (likely 1-1/8" or 1-3/8") and the bolt circle for blade mounting holes. This pan uses a specific 4-bolt pattern – count your existing holes and measure center-to-center.
• OEM vs aftermarket: This is an OEM Rotary part. Aftermarket pans may have different thickness or hole positions. If you’re replacing a worn pan, measure your old one’s thickness (typically 3/8" to 1/2") and match it.

Key Things to Know

• Installation difficulty: Moderate. You’ll need a torque wrench, impact gun, and likely a gear puller to remove the old pan. Expect 1-2 hours if you’re mechanically inclined.
• Common gotcha: The retaining nut is often staked or lock-tited from the factory. Heat or a breaker bar may be required to break it free. Replace the nut or keyway if damaged.
• Blade compatibility: This pan accepts standard 3/4" hole blades used on 40hp cutters. Ensure your blades have the correct offset and length for your deck width (typically 5-6 ft).
• Wear indicator: Check the pan’s underside for cracks near the blade bolt holes. If you see hairline cracks, replace immediately – a failure at speed can cause serious damage.

Should You Buy It

Buy this if you have a Rotary-brand 40hp cutter with a worn or cracked blade pan and want a direct OEM replacement that bolts on without guesswork. Skip it if you’re on a tight budget (aftermarket pans run $80-120) or if your cutter is a different brand – you’ll likely need adapter plates or a different part number.