Bush Hog 4120
Double tap to zoom
4120
FW4120 Flex-Wing Rotary Cutter
Overview:
The FW4120 may be big, but it is no slumbering giant. Packed with upgraded, heavy-duty features that build on the legacy of the popular 2820 Series merged with the style of our 4115 and 5115 Series, these 20′ Flex-Wings are perfectly at home in a variety of applications like mowing pastures, cleaning up row crop residue, taking down tough CRP, and long days maintaining roadsides. Designed to cut heavy grasses and brush up to 4” in diameter, these cutters get the job done in virtually any mowing environment, except small neighborhood yards with garden gnomes. It would destroy the gnomes.
New performance and convenience features like heavily modified axles with an 8-point suspension, EZ-change blade bolts, and EZ-adjust leveling rods make your life easier. Our new and improved axles glide over obstacles, while significantly reducing shock loads for an improvement you can see and feel in the tractor seat. Heavily-braced, 7ga smooth-top decks shed debris and water for easier cleanup. Gearbox stand plates are thicker and gusseted for improved strength and durability. Hooking up to your tractor just got easier with a more adjustable tongue height range and quality of life features like rollover and clevis stops in our updated Perma-Level+ Hitch. Standard equipment includes Deck Rings and convenience features like EZ-lube drivelines, hydraulic hose handles to reduce slipping and improve ergonomics, and a Patent-Pending Driveline Assist that lifts and holds the weight of the heavy CV Driveline while attaching or removing from the tractor PTO. Then when not in use, the hoses and Driveline Assist can be safely stored in the tongue.
The New FW4120 20′ Flex-Wing can be equipped with Round Pans or a Shredder Bar, Perma-Level+ or 2 5/16″ Ball Hitch, 540 or 1,000 PTO Driveline, Center Dual or Walking Tandem Axles, Wing Single, Dual, or Walking Tandem Axles, 21″ or 25″ Laminated, 27″ or 29″ Air-Filled, or 25″ Foam-Filled Tires, and Single or Double Row Chains. And as with all Bush Hog® Rotary Cutters, the New FW4120 Flex-Wing comes with the industry’s first 10-Year Gearbox Limited Warranty. To show our confidence in the durability of the New 41 Series Flex-Wings, we have increased the Machine Limited Warranty to 2 years. That’s another reason why, “If it doesn’t say Bush Hog®, it just won’t cut it.”
Get A Quote
Fields with asterisks* are required. Please email our helpful staff with any questions or comments using the contact form.
Loan Calculator
Use the Loan Calculator to help you determine the financing and payment options that are best for you.
**The accuracy of this calculator and its applicability to your circumstances is not guaranteed. You should obtain personal advice from qualified professionals. This information is provided for illustrative purposes only and does not constitute an application. This notice does not guarantee loan approval, nor is it an offer or commitment to make a loan to you on the above terms.
Send To A Friend
Fields with asterisks* are required. Your friend will receive an email that contains a reference to this page. Please send this email only to people you know who would be interested in this information.
Features
Performance Features
- New Patent-Pending axle suspension reduces g-force shock loads by 37%
- Replaceable 1/2″ Cast Wing Skids for extended wear during heavy ground contact
- Angled rear deck section with 41% longer skids improve durability during side and backward impacts
- New durable Cast Leveling Rod Cams make adjusting deck pitch easier
- New Cast Walking Tandem Axles walk over the most rugged terrain instead of bounce through it
- Center section axle spindles are centered on the axle arm for equalized loading of vertical forces
- Grease fittings and spring steel bushings at axle pivot points for longer life
- Wing decks free float 22° down and 45° up without engaging the hydraulic cylinder for longer cylinder life
- Wing axles are adjustable left to right for variable row crop spacings
- New Rollover and Clevis Stops on the Perma-Level+ Hitch make tractor hookups easier
- Increased Cutting and Transport Height to mow down taller vegetation and easier loading on trailers
Construction Features
- Industry first — 3″ O.D. output shaft in cutting gearboxes
- Smooth-top 7ga deck plates are heavily-reinforced for years of trouble-free service
- Stronger gearbox mount and stand are built to withstand years of punishing mowing conditions
- Blade pans come standard with Hardened Hex-Head Blade Bolts and Bushings for easy blade changes
- 194% increase in axle arm section for substantially improved strength
- ASAE Cat 6 Input Drivelines and ASAE Cat 5 Wing Drivelines for strength in heavy cutting conditions
- Grease fittings in our E-Z lube drivelines align for reduced service times
- Patented oil sight windows make for quick and easy oil level checks
- Large, replaceable skids behind the tongue protect deck structure from ground contact
Safety Features
- Single or Double Row Chains to knock down flying debris
- Transport Lock supports the cutter while transporting
- Wing locks hold the wings stable when in an upright position
- Rollover and Clevis Stops reduce rotating and swinging hitch components while attaching to tractor drawbar
- 360° coverage around rotating drivelines
- LED safety lighting standard
Product Features
- (4) custom-tuned rubber isolators on the center axle absorb damaging shock loads before going through the deck and eventually to the tractor
- Improved structural framework with durable Deck Rings standard
- New Cast Walking Tandem Axle selection strolls over rough terrain with ease
- Axle Arms increased from 5.25″ x 6.5″ welded channel to 6″ x 8″ structural tube for superior strength in this high-stress area
- The SR1 model is equipped with two additional flat blades per cutting circle that can be fitted with an optional cross bar and two additional blades.
- Each axle cuff houses a performance-matched rubber isolator to reduce shock from the moment it begins
- 1/2″ replaceable cast skids and longer formed skids help protect the 1/4″ x 13″ sidebands
- Round Pan with Hardened Hex-Head Blade Bolts and Bushings make blade changes quick and easy
- Take the load off with our Patent Pending Driveline Assist that raises heavy CV Drivelines into tractor PTO position
- The optional Shredder Kit adds a crossbar and two additional blades to the SR1 Model
Specifications
| Models | 4120 |
| Cutting Width | 20′ |
| Cutting Height | 1 1/2″ - 16″ |
| Cutting Capacity | 4″ |
| Transport Width* | 9′ 8″ |
| Transport Height** | 9′ |
| Transport Length*** | 19′ 9″ |
| Approximate Weight (lb.) | 7,300 |
| Approximate Tongue Weight (lb.) | 2,600 |
| Minimum Tractor PTO HP | 90 |
| Hitch | "Perma-Level+" or Ball Hitch |
| Center Deck | 7ga |
| Wing Decks | 7ga |
| Wing Cutting Angles | 22° Down and 45° Up |
| Wing Level Adjustment | Turnbuckles |
| Sidebands | 1/4″ x 13 1/2″ |
| Transfer Gearbox (HP) | 250 |
| Cutting Gearboxes (HP) | 225 |
| Input Driveline | Category 6 |
| Wing Drivelines | Category 5 |
| Blade Holder | 7ga Round |
| Blades | 1/2″ x 4″ |
| Blade Tip Speed (fpm) | 15,750 |
| Axle Suspension | Isolator in Each Axle Cuff + (4) Isolators in Center Isolator Bank |
| Center & Wing Hydraulics | 3 Hoses |
| PTO Driveline Assist | Standard |
| Safety Tow Chain | Standard |
| Distribution Baffles | Optional |
| Wing Gauge Wheels | Optional |



