321

Medium Excavators 321

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Key Specs

Net Power - ISO 9249
129 hp
96 kW
Operating Weight
42,600 lb
19300 kg
Maximum Digging Depth
19.6 ft
5970 mm

Overview

Versatility at the Lowest Cost Per Hour

Powered by the reliable Cat® C3.6 engine, the Cat® 321 excavator delivers high torque and fast cycle times to maximize productivity. Reinforced Cat structures extend machine life and withstand the toughest conditions, while the latest cab design puts operator safety and comfort first. Every core system undergoes rigorous testing, so you can count on consistent, reliable performance shift after shift.

Benefits

Performance You Can Feel

A reliable Cat® C3.6 engine delivers high torque and fast cycle times. The integrated Engine Control Module (ECM) ensures smooth, precise operation. Advanced electrohydraulic (EH) system optimize fuel consumption without sacrificing digging force or controllability. 

Built To Last

Reinforced Cat structures are engineered to tackle demanding applications, extending machine life in harsh environments. Two undercarriage options provide excellent stability and long-lasting durability on rugged terrain. Every system is tested and proven to perform through long, demanding shifts with a wide range of work tools.

Less Downtime. Low Costs.

Extended, synchronized service intervals reduce downtime and keep maintenance costs low. Shared Cat components simplify maintenance and increase parts availability, especially across mixed fleets. The latest cab design helps improve operator visibility, control, and comfort. 

Product Specifications for 321

Net Power - ISO 9249 129 hp 96 kW
Net Power - ISO 9249 (DIN) 131 hp (metric) 131 hp (metric)
Engine Model Cat® C3.6 Cat® C3.6
Engine Power - ISO 14396 134 hp 100 kW
Engine Power - ISO 14396 (DIN) 136 hp (metric) 136 hp (metric)
Bore 4 in 98 mm
Stroke 5 in 120 mm
Displacement 220 in³ 3.6 l
Biodiesel Capability Up to B20¹ Up to B20¹
Emissions Non-certified emission engine. Non-certified emission engine.
Note (1) Net power advertised is the power available at the flywheel when the engine is equipped with fan, air intake system, exhaust system and alternator with engine speed at 2,000 rpm. Advertised power is tested per the specified standard in effect at the time of manufacture. Net power advertised is the power available at the flywheel when the engine is equipped with fan, air intake system, exhaust system and alternator with engine speed at 2,000 rpm. Advertised power is tested per the specified standard in effect at the time of manufacture.
Note (2) ¹Cat® engines are compatible with diesel fuel blended with the following lower-carbon intensity fuels** up to: 100% biodiesel FAME (fatty acid methyl ester)* or 100% renewable diesel, HVO (hydrotreated vegetable oil) and GTL (gas-to-liquid) fuels. Refer to guidelines for successful application. Please consult your Cat dealer or “Caterpillar Machine Fluids Recommendations” (SEBU6250) for details. *For use of blends higher than 20% biodiesel, consult your Cat dealer. **Tailpipe greenhouse gas emissions from lower-carbon intensity fuels are essentially the same as traditional fuels. ¹Cat® engines are compatible with diesel fuel blended with the following lower-carbon intensity fuels** up to: 100% biodiesel FAME (fatty acid methyl ester)* or 100% renewable diesel, HVO (hydrotreated vegetable oil) and GTL (gas-to-liquid) fuels. Refer to guidelines for successful application. Please consult your Cat dealer or “Caterpillar Machine Fluids Recommendations” (SEBU6250) for details. *For use of blends higher than 20% biodiesel, consult your Cat dealer. **Tailpipe greenhouse gas emissions from lower-carbon intensity fuels are essentially the same as traditional fuels.
Operating Weight 42,600 lb 19300 kg
Note 4.1 m (13'5") Standard undercarriage, 5.7 m (18'8") Reach boom, R2.25 (7'5") stick, 1 m3 (1.31 yd3) General Duty (GD) bucket, 600 mm (24") triple grouser track shoes and 3650 kg (8,050 lb) counterweight. 4.1 m (13'5") Standard undercarriage, 5.7 m (18'8") Reach boom, R2.25 (7'5") stick, 1 m3 (1.31 yd3) General Duty (GD) bucket, 600 mm (24") triple grouser track shoes and 3650 kg (8,050 lb) counterweight.
Maximum Digging Depth 19.6 ft 5970 mm
Boom Reach 5.7 m (18'8") Reach 5.7 m (18'8")
Stick Reach 2.25 m (7'5") Reach 2.25 m (7'5")
Bucket GD 1 m³ (1.31 yd³) GD 1 m³ (1.31 yd³)
Maximum Reach at Ground Level 30 ft 9150 mm
Maximum Cutting Height 29.9 ft 9120 mm
Maximum Loading Height 20.5 ft 6250 mm
Minimum Loading Height 9.6 ft 2920 mm
Maximum Depth Cut for 2440 mm (8 ft) Level Bottom 18.9 ft 5760 mm
Maximum Vertical Wall Digging Depth 17.6 ft 5360 mm
Bucket Digging Force - ISO 30280 lbf 135 kN
Stick Digging Force - ISO 26800 lbf 119 kN
Main System - Maximum Flow 315 l/min (83 gal/min) 315 l/min (83 gal/min)
Maximum Pressure - Equipment 5075 psi 35000 kPa
Maximum Pressure - Travel 5075 psi 35000 kPa
Maximum Pressure - Swing 3625 psi 25000 kPa
Swing Speed 10 r/min 10 r/min
Maximum Swing Torque 45260 lbf·ft 61 kN·m
Fuel Tank Capacity 97.7 gal (US) 370 l
Cooling System 6.6 gal (US) 25 l
Engine Oil 2.9 gal (US) 11 l
Swing Drive - Each 1.6 gal (US) 6 l
Final Drive - Each 1.6 gal (US) 6 l
Hydraulic System - Including Tank 57.6 gal (US) 218 l
Hydraulic Tank 30.4 gal (US) 115 l
Boom Reach 5.7 m (18'8") Reach 5.7 m (18'8")
Stick Reach 2.25 m (7'5") Reach 2.25 m (7'5")
Bucket GD 1 m³ (1.31 yd³) GD 1 m³ (1.31 yd³)
Shipping Height - Top of Cab 10.7 ft 3250 mm
Handrail Height 9.9 ft 3010 mm
Shipping Length 31.4 ft 9570 mm
Tail Swing Radius 9.3 ft 2830 mm
Counterweight Clearance 3.3 ft 1020 mm
Ground Clearance 1.4 ft 430 mm
Track Length 13.4 ft 4080 mm
Length to Center of Rollers 10.7 ft 3270 mm
Track Gauge 7.2 ft 2200 mm
Transport Width 9.2 ft 2800 mm

321 Standard Equipment

NOTE

  • Standard and optional equipment may vary. Consult your Cat dealer for details.

BOOM, STICKS AND LINKAGE

  • 5.7 m (18'8") Reach boom
  • Bucket linkage, B1 family with lifting eye

CAB

  • Sound suppressed cab with viscous mounts
  • Mechanical-suspension seat with headrest and armrest angle adjustment
  • High-resolution 203 mm (8") LCD touchscreen monitor
  • Keyless push to start engine control
  • AM/FM Bluetooth® radio with USB/Auxiliary ports
  • Cup holder and storage compartments
  • Upper radial wiper with washer
  • Openable steel hatch
  • Washable floor mat
  • 51 mm (2") orange seat belt

CAT TECHNOLOGY

  • VisionLink™

ELECTRICAL SYSTEM

  • Two 750 CCA maintenance free batteries
  • Simplified electrohydraulic control system/harness
  • Centralized electrical disconnect switch
  • LED chassis and cab light
  • LED left-side boom light

ENGINE

  • Cat C3.6 single turbo diesel engine
  • Three selectable modes: Power, Smart, Eco
  • One-touch low idle with automatic engine speed control (AEC)
  • Two stage fuel filtration system with water separator and indicator
  • 4000 m (13,120 ft) altitude capability with derate from 3000 m (9,840 ft)
  • 52°C (126° F) high-ambient cooling capacity with derate above 48°C (118° F)
  • -10° C (14° F) cold start capability
  • 100 Amp. alternator
  • Radial seal air filter with double filter element
  • Electric fuel priming pump

HYDRAULIC SYSTEM

  • Electronic main control valve, hammer ready
  • Boom and stick regeneration circuits
  • Automatic hydraulic warm-up
  • Automatic two speed travel
  • High performance hydraulic return filter

SAFETY AND SECURITY

  • Rearview mirrors; handrail mounted (one), cab handhold mounted (one)
  • Bolt free service platform with anti-skid plate
  • Neutral lever (lock out) for all controls
  • Ground level accessible secondary engine shutoff switch in cab
  • Handrail and handhold
  • Signaling/warning horn

SERVICE AND MAINTENANCE

  • Scheduled Oil Sampling (S·O·S℠) ports
  • Radiator screen for radiator/oil cooler to prevent plugging by debris

UNDERCARRIAGE AND STRUCTURES

  • Grease lubricated track links
  • Bottom guard
  • Center track guiding guard
  • 3650 kg (8,050 lb) counterweight
  • 600 mm (24 in) triple grouser shoes (8.5 mm/0.34" thick)
  • 3650 kg (8,050 lb) counterweight
  • 600 mm (24 in) triple grouser shoes (8.5 mm/0.34" thick)

321 Optional Equipment

NOTE

  • Standard and optional equipment may vary. Consult your Cat dealer for details.

BOOM, STICKS AND LINKAGE

  • 2.25 m (7'5") Reach stick
  • 2.5 m (8'2") Reach stick

CAB

  • Front windshield guard (wire mesh)

ELECTRICAL SYSTEM

  • LED right-side boom light

HYDRAULIC SYSTEM

  • Hydraulic auxiliary lines (hammer)

SAFETY AND SECURITY

  • Rearview camera
  • Travel alarm

UNDERCARRIAGE AND STRUCTURES

  • 4.1 m (13'5") Standard undercarriage
  • 4.25 m (13'11") Medium undercarriage

See how 321 compares against frequently compared products.

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321 Hydraulic Excavator

321 Hydraulic Excavator

321 Hydraulic Excavator

321 Hydraulic Excavator

321 Hydraulic Excavator

321 Hydraulic Excavator

321 Hydraulic Excavator

321 Hydraulic Excavator

321 Hydraulic Excavator
321 Hydraulic Excavator
321 Hydraulic Excavator
321 Hydraulic Excavator
321 Hydraulic Excavator
321 Hydraulic Excavator
321 Hydraulic Excavator
321 Hydraulic Excavator

Introducing Next Generation Cat® Excavator 321

Introducing Next Generation Cat® Excavator 321

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