The reliable Cat C3.6 engine delivers high torque and fast cycle times for maximum productivity. Its integrated engine control module (ECM) ensures smooth, precise operation, while the advanced electrohydraulic (EH) system intelligently manages fuel use, optimizing efficiency without sacrificing digging power or controllability.
Reinforced Cat structures are engineered to take on the toughest applications, delivering exceptional durability and extended machine life in harsh conditions. Two robust undercarriage options provide superior stability and long-lasting performance on rugged terrain. Every system is tested and proven to deliver dependable results, day after day, shift after shift, no matter the job.
Extended and synchronized service intervals help you stay on the job longer and reduce overall maintenance costs. Shared Cat components make servicing easier and improve parts availability, especially across mixed fleets, keeping your operations running efficiently. Inside, the latest cab design enhances visibility, control, and comfort, helping operators perform at their best through every shift.
Engine power and electrohydraulic precision are perfectly synchronized to maximize productivity. Eco Mode helps you lower fuel use without sacrificing performance, while adaptive engine controls and the Intelligent ECM provide smooth, consistent responsiveness through every cut, swing, and load.
Automatic Engine Control reduces engine speed during idle, saving fuel whenever the machine pauses. Boom and stick regeneration circuits further improve cycle times and controllability, delivering faster, smoother performance. A durable, multi-stage fuel filtration system protects against contaminants to keep your excavator running cleaner and longer.
Shift after shift, your Cat excavator delivers the efficiency, reliability, and versatility that keep your business moving forward. Lower fuel costs, less downtime, and proven Cat durability add up to stronger performance and more profit potential, built into every machine.
On a busy jobsite, safety isn't optional, it's built into the 321. Clear sightlines, standard mirrors, and an optional rearview camera boost confidence in tight spaces. An optional front windshield guard adds protection from rocks, debris, and other unexpected hazards.
A heavy-duty base frame and reinforced "X" car body deliver stability that meets ISO 15818:2017 lifting and tie-down standards, while serrated steps, anti-skid plating, and compliant handrails help prevent slips and falls. Ground-level service points keep daily checks quick and safe, while a lockable battery disconnect switch ensures secure servicing.
Bright LED lights illuminate the jobsite, while a quiet muffler and reinforced cab create a safe, more comfortable environment. Wide entry doors, bright seatbelts, emergency exits, and an optional travel alarm keep operators visible, supported, and confident every second of every shift.
| Net Power - ISO 9249 | 129 HP |
| Engine Model | CAT® C3.6 |
| Engine Power - ISO 14396 | 134 HP |
| Bore | 4 in |
| Stroke | 5 in |
| Displacement | 220 in³ |
| Main System - Maximum Flow | 315 l/min (83 gal/min) |
| Maximum Pressure - Equipment | 5075 psi |
| Maximum Pressure - Travel | 5075 psi |
| Maximum Pressure - Swing | 3625 psi |
| Swing Speed | 10 r/min |
| Maximum Swing Torque | 45260 ft·lbf |
| Operating Weight | 42600 lb |
| Fuel Tank Capacity | 97.7 gal (US) |
| Cooling System | 5.8 gal (US) |
| Engine Oil | 2.9 gal (US) |
| Swing Drive - Each | 1.6 gal (US) |
| Final Drive - Each | 1.6 gal (US) |
| Hydraulic System - Including Tank | 57.6 gal (US) |
| Hydraulic Tank | 30.4 gal (US) |
| Boom | Reach 5.7 m (18'8") |
| Stick | Reach 2.25 m (7'5") |
| Bucket | GD 1.0 m³ (1.31 yd³) |
| Undercarriage | Standard |
| Shipping Height - Top of Cab | 10.7 ft |
| Handrail Height | 9.9 ft |
| Machine Length (with boom, stick, bucket installed) | 31.4 ft |
| Tail Swing Radius | 9.3 ft |
| Counterweight Clearance | 3.3 ft |
| Ground Clearance | 1.4 ft |
| Track Length | 13.4 ft |
| Length to Center of Rollers | 10.7 ft |
| Track Gauge - Under Carriage | 7.2 ft |
| Transport Width - 600 mm (24") shoes | 9.2 ft |
| Maximum Digging Depth | 19.6 ft |
| Boom | Reach 5.7 m (18'8") |
| Stick | Reach 2.25 m (7'5") |
| Bucket | GD 1.0 m³ (1.31 yd³) |
| Maximum Digging Depth | 19.6 ft |
| Maximum Reach at Ground Level | 30 ft |
| Maximum Cutting Height | 29.9 ft |
| Maximum Loading Height | 20.5 ft |
| Minimum Loading Height | 9.6 ft |
| Maximum Depth Cut for 2440 mm (8 ft) Level Bottom | 18.9 ft |
| Maximum Vertical Wall Digging Depth | 17.6 ft |
| Bucket Digging Force - ISO | 30280 lbf |
| Stick Digging Force - ISO | 26800 lbf |
Cat buckets and Cat Ground Engaging Tools (GET) are designed and matched to the machine to ensure optimal performance and fuel efficiency.
Center-Lock is a pin grabber coupler and features a patent-pending locking system. A highly visible secondary lock clearly shows the operator when the coupler is engaged or disengaged from the bucket or work tool..
Cat® Hammers make short work of your demolition, construction, and quarry needs. Combine the simple, lightweight design of the GC Hammer series with the reliability, durability, and value you expect from Cat products. The result is a low cost per hour solution providing the consistent power and performance you need.
Constructed from high-strength steels and built to last, Cat rippers endure in the toughest conditions. The box-section structure is reinforced for maximum rigidity, transmitting the full machine power to the material being ripped. Rippers feature a replaceable wear tip, and most models also come equipped with a replaceable shank protector.
Cat grapples make Cat excavators the ideal machine for handling loose material, sorting trash, and demolition site cleanup. An array of styles and sizes is available to match excavators to the task at hand.
Multi-processors do the work of many types of demolition tools by use of interchangeable jaw sets. Changing jaws allows a single unit to crush, pulverize, and perform a variety of specialized tasks such as cutting steel rebar and tanks.
Cat shears are designed to take full advantage of the hydraulic flows and pressures produced by Cat excavators – all to enhance productivity without compromising safety or causing premature wear of the shear or carrier.
Mechanical pulverizers are cost-effective tools for recycling demolished concrete debris. The bucket cylinder on the excavator powers the pulverizer, eliminating the need for a dedicated cylinder, associated hydraulics, and additional installation cost.
Cat compactors make job site compaction quick, efficient, and cost effective.
The hydraulic concrete crusher is well suited for demolition in residential areas. The tool combines several demolition operations in one piece of equipment:
