321 Medium Excavators

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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

321
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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.

Features At A Glance

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Delivering Excellent Fuel Efficiency

The Cat C3.6 engine and electrohydraulic system work in sync to help you move plenty of material while using less fuel.
Eco mode reduces fuel consumption with no loss in lifting or digging forces.
Adaptive engine control adjustments for maximized efficiency.
Electro-hydraulic (EH) system eliminates the need for pilot lines and filter for improved response and enhanced savings.
Intelligent Engine Control Module (ECM) ensures smooth, precise operation in every pass.
Save fuel with Automatic Engine Control (AEC). It reduces engine speed when the machine is not under load to minimize fuel consumption.
Robust and easy-to-maintain fuel system filtration reduces risk of failure from contaminated fuel.
Boom and Stick regeneration circuits reduce fuel consumption while improving cycle times.
Protect hydraulic components in cold weather. The auto warm-up feature speeds hydraulic oil warming in cooler temperatures.
No derating up to 3,000 m (9,840 ft) above sea level.
The excavator has a high-ambient temperature capability of 52º C (126º F) and cold start capability of –10° C (14° F).

Built To Last

Reinforced Cat structures extend machine life in harsh working conditions.
The strong X-structure lower frame carries loads from the excavator's upper structure to the track.
Reliable and durable and built on classic, proven components.
Robotically welded booms and sticks ensure structural integrity.
Track guards and steep-angle design shed debris, reducing wear.
Choose between two robust undercarriage options: standard 4.1 m (13'5") or optional medium 4.25 m (13'11"), both built to withstand demanding conditions.
The single plane cooling package design reduces air resistance compared to the traditional two-plane design for better cooling performance and enhanced machine productivity.
Sloped track frame helps prevent mud and debris from accumulating in the track area.
The center track guiding guard helps align the excavator track when traveling and working on slopes.
Robust bottom guards protect machine components that might be damaged while swinging.
High swing speed and proven Cat components keep you working longer.
Hydraulic lines protected inside the frame reduce damage risk.
Choose from three bucket options, including a 1.0 m³ (1.31 yd³) General Duty bucket for efficient earthmoving and quick discharge, a 0.92 m³ (1.20 yd³) Heavy Duty bucket for more demanding applications, and a 1.2 m³ (1.57 yd³) General Duty bucket for sand‑mining applications.
Auto warm-up speeds up hydraulic oil warming in cold temperatures and helps prolong the life of components.
Choose the 2.25 m (7'5") stick for maximum lifting and breakout force, the 2.5 m (8'2") stick for extended reach and versatility, or the R2.9 (9'6") Reach stick for enhanced reach in sand excavation and loading.
Smart, Power and Eco modes let you tailor machine performance by adapting to the job, maximizing productivity or reducing fuel costs.

Low Maintenance, More Uptime

The 321 features a safe, convenient work platform for routine service and maintenance. Anti-skid plating with countersunk bolts reduces slip and trip hazards, while integrated grips on key areas ensure easy access to the platform and operator station.
Shared components simplify maintenance and improve parts availability.
Scheduled Oil Sampling (S·O·S^SM) ports are on ground level, simplifying maintenance and allowing for quick, easy extraction of samples for fluid analysis.
Extended and synchronized service intervals save on maintenance costs.
Extended first engine oil change interval (500 hours), and maintenance-free batteries.
Filters, such as fuel, engine air, and oil filters, are grouped together for easy access and preventative maintenance.
There is no need to manually prime the fuel system after fuel filter changes. The standard electric priming pump reduces the risk of contamination by preventing unfiltered fuel from entering the fuel system.
Maximize uptime and extended service intervals, thanks to advanced hydraulic oil filter design and no pilot and case drain filters.
A two-stage fuel filter and anti-rust fuel tank help protect the engine against low-quality fuel.
Routine cleaning is made easier with the single plane cooling package design.
Proven, high-efficiency radial seal engine air filter behind the cab. The machine constantly monitors the engine air filter and will notify you, via the monitor, when service is required.
The latest air intake filter with pre-cleaner has double the dust holding capacity of the previous air intake filter.

Safety First, Always

The latest cab provides excellent visibility from the operator’s seat. In addition, two standard mirrors help keep you aware of your surroundings.
Optional rearview camera enhances visibility behind the machine.
Optional front windshield guard helps protect the windshield from potential damage caused by rocks, flying debris, and other road materials.
Heavy-duty base frame and reinforced “X” car body conform to ISO 15818:2017 lifting and tie-down requirements.
Handrails and hand hold with a step on the undercarriage for easy access to the engine bay area. The handrails conform to ISO 2867:2011 requirements for added safety.
Anti-skid plating with countersunk bolts reduces the potential for slippage and trip hazards.
Ground-level access for daily checks improves safety and saves time.
Serrated steps, anti-skid plating, and handrails help you avoid slips and trips – a major contributor to workplace injuries.
A lockable disconnect switch isolates the battery and enhances safety by disconnecting the electrical energy when servicing the machine.
The optional travel alarm provides a clear warning signal, alerting nearby individuals to the machine's movement and promoting a safe working environment.
Bright seatbelts and a wide cab entry improve safety and usability.
LED 1200 lumen lights, a quiet muffler, and emergency cab exits support 24/7 operation.

Simple To Operate

Start the engine with a push button.
The in-cab high-resolution 203 mm (8 in) touchscreen monitor is easy to use, intuitive, and user-friendly.
Continuously improved user interface allows for intuitive navigation, minimizing performance interruption with the easy-to-use touchscreen menu.
The machine’s electrohydraulic system allows accurate bucket control for maximum precision.
Optimized low-effort joystick controls reduce operator fatigue.
Customize joystick patterns and preferences; the machine remembers each operator's settings.
Auto hammer stop protects tools from overheating and wear.

Comfort That Keeps You Going

Ergonomically designed seat to improve operator’s comfort.
Sound suppression, seals, and viscous cab mounts decrease noise and vibration for a quieter work environment.
Standard automatic climate control helps keep you comfortable all shift long.
Excellent work site visibility from the cab enhances productivity and safety.
Adjustable seat with three suspension levels and ergonomic design.
Climate control, Bluetooth® connectivity, USB ports, and an intuitive interface enhance comfort.
Control the excavator comfortably with easy-to-reach controls all located in front of you.
Easy to access radio controls, engine throttle, wiper controls and Bluetooth phone pairing for operator convenience.
Automatic climate control helps maintain consistent cab temperature. Five outlets ensure proper air circulation to keep you comfortable regardless of outside temperatures.
There is plenty of room for you to store your gear. The cup holder and storage space in front of the controls can hold large cups and wide cell phones; storage behind the seat can hold a large lunchbox and other items.
Bright seatbelts and a wide cab entry improve safety and usability.

The Cat C3.6 engine and electrohydraulic system work in sync to help you move plenty of material while using less fuel.
Eco mode reduces fuel consumption with no loss in lifting or digging forces.
Adaptive engine control adjustments for maximized efficiency.
Electro-hydraulic (EH) system eliminates the need for pilot lines and filter for improved response and enhanced savings.
Intelligent Engine Control Module (ECM) ensures smooth, precise operation in every pass.
Save fuel with Automatic Engine Control (AEC). It reduces engine speed when the machine is not under load to minimize fuel consumption.
Robust and easy-to-maintain fuel system filtration reduces risk of failure from contaminated fuel.
Boom and Stick regeneration circuits reduce fuel consumption while improving cycle times.
Protect hydraulic components in cold weather. The auto warm-up feature speeds hydraulic oil warming in cooler temperatures.
No derating up to 3,000 m (9,840 ft) above sea level.
The excavator has a high-ambient temperature capability of 52º C (126º F) and cold start capability of –10° C (14° F).

Reinforced Cat structures extend machine life in harsh working conditions.
The strong X-structure lower frame carries loads from the excavator's upper structure to the track.
Reliable and durable and built on classic, proven components.
Robotically welded booms and sticks ensure structural integrity.
Track guards and steep-angle design shed debris, reducing wear.
Choose between two robust undercarriage options: standard 4.1 m (13'5") or optional medium 4.25 m (13'11"), both built to withstand demanding conditions.
The single plane cooling package design reduces air resistance compared to the traditional two-plane design for better cooling performance and enhanced machine productivity.
Sloped track frame helps prevent mud and debris from accumulating in the track area.
The center track guiding guard helps align the excavator track when traveling and working on slopes.
Robust bottom guards protect machine components that might be damaged while swinging.
High swing speed and proven Cat components keep you working longer.
Hydraulic lines protected inside the frame reduce damage risk.
Choose from three bucket options, including a 1.0 m³ (1.31 yd³) General Duty bucket for efficient earthmoving and quick discharge, a 0.92 m³ (1.20 yd³) Heavy Duty bucket for more demanding applications, and a 1.2 m³ (1.57 yd³) General Duty bucket for sand‑mining applications.
Auto warm-up speeds up hydraulic oil warming in cold temperatures and helps prolong the life of components.
Choose the 2.25 m (7'5") stick for maximum lifting and breakout force, the 2.5 m (8'2") stick for extended reach and versatility, or the R2.9 (9'6") Reach stick for enhanced reach in sand excavation and loading.
Smart, Power and Eco modes let you tailor machine performance by adapting to the job, maximizing productivity or reducing fuel costs.

The 321 features a safe, convenient work platform for routine service and maintenance. Anti-skid plating with countersunk bolts reduces slip and trip hazards, while integrated grips on key areas ensure easy access to the platform and operator station.
Shared components simplify maintenance and improve parts availability.
Scheduled Oil Sampling (S·O·S^SM) ports are on ground level, simplifying maintenance and allowing for quick, easy extraction of samples for fluid analysis.
Extended and synchronized service intervals save on maintenance costs.
Extended first engine oil change interval (500 hours), and maintenance-free batteries.
Filters, such as fuel, engine air, and oil filters, are grouped together for easy access and preventative maintenance.
There is no need to manually prime the fuel system after fuel filter changes. The standard electric priming pump reduces the risk of contamination by preventing unfiltered fuel from entering the fuel system.
Maximize uptime and extended service intervals, thanks to advanced hydraulic oil filter design and no pilot and case drain filters.
A two-stage fuel filter and anti-rust fuel tank help protect the engine against low-quality fuel.
Routine cleaning is made easier with the single plane cooling package design.
Proven, high-efficiency radial seal engine air filter behind the cab. The machine constantly monitors the engine air filter and will notify you, via the monitor, when service is required.
The latest air intake filter with pre-cleaner has double the dust holding capacity of the previous air intake filter.

The latest cab provides excellent visibility from the operator’s seat. In addition, two standard mirrors help keep you aware of your surroundings.
Optional rearview camera enhances visibility behind the machine.
Optional front windshield guard helps protect the windshield from potential damage caused by rocks, flying debris, and other road materials.
Heavy-duty base frame and reinforced “X” car body conform to ISO 15818:2017 lifting and tie-down requirements.
Handrails and hand hold with a step on the undercarriage for easy access to the engine bay area. The handrails conform to ISO 2867:2011 requirements for added safety.
Anti-skid plating with countersunk bolts reduces the potential for slippage and trip hazards.
Ground-level access for daily checks improves safety and saves time.
Serrated steps, anti-skid plating, and handrails help you avoid slips and trips – a major contributor to workplace injuries.
A lockable disconnect switch isolates the battery and enhances safety by disconnecting the electrical energy when servicing the machine.
The optional travel alarm provides a clear warning signal, alerting nearby individuals to the machine's movement and promoting a safe working environment.
Bright seatbelts and a wide cab entry improve safety and usability.
LED 1200 lumen lights, a quiet muffler, and emergency cab exits support 24/7 operation.

Start the engine with a push button.
The in-cab high-resolution 203 mm (8 in) touchscreen monitor is easy to use, intuitive, and user-friendly.
Continuously improved user interface allows for intuitive navigation, minimizing performance interruption with the easy-to-use touchscreen menu.
The machine’s electrohydraulic system allows accurate bucket control for maximum precision.
Optimized low-effort joystick controls reduce operator fatigue.
Customize joystick patterns and preferences; the machine remembers each operator's settings.
Auto hammer stop protects tools from overheating and wear.

Ergonomically designed seat to improve operator’s comfort.
Sound suppression, seals, and viscous cab mounts decrease noise and vibration for a quieter work environment.
Standard automatic climate control helps keep you comfortable all shift long.
Excellent work site visibility from the cab enhances productivity and safety.
Adjustable seat with three suspension levels and ergonomic design.
Climate control, Bluetooth® connectivity, USB ports, and an intuitive interface enhance comfort.
Control the excavator comfortably with easy-to-reach controls all located in front of you.
Easy to access radio controls, engine throttle, wiper controls and Bluetooth phone pairing for operator convenience.
Automatic climate control helps maintain consistent cab temperature. Five outlets ensure proper air circulation to keep you comfortable regardless of outside temperatures.
There is plenty of room for you to store your gear. The cup holder and storage space in front of the controls can hold large cups and wide cell phones; storage behind the seat can hold a large lunchbox and other items.
Bright seatbelts and a wide cab entry improve safety and usability.

VisionLink™ wirelessly connects you to your equipment, giving you access to essential information you need to know to run your business. Gain valuable insight into how your machine or fleet is performing. Access data anywhere—desktop, tablet, or mobile device.
Available CVA (Customer Value Agreements) and EPP (Extended Protection Plans) help maximize uptime and reduce risk.
Cat dealers are second to none. From machine selection and purchase to maintenance support, operator training and rebuilds, Cat dealers have the experience and capabilities to help keep you up and running at peak performance.

Specifications Standard Equipment Optional Equipment

Product Specifications for 321

Engine

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.

Weights

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.

Working Ranges and Forces

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

Hydraulic System

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 Mechanism

Swing Speed	10 r/min 10 r/min
Maximum Swing Torque	45260 lbf·ft 61 kN·m

Service Refill Capacities

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

Dimensions

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)

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

2.9 m (9'6") 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

Product Specifications for 321

Download Print

Engine

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.

Weights

Operating Weight

42,600 lb 19300 kg

Note

Working Ranges and Forces

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

Hydraulic System

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 Mechanism

Swing Speed	10 r/min 10 r/min
Maximum Swing Torque	45260 lbf·ft 61 kN·m

Service Refill Capacities

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

Dimensions

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)

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

2.9 m (9'6") 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

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Excavators

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321

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

Excavators

320 GX Tier 3

Net Power - ISO 9249: 139 hp; 103.6 kW
Operating Weight: 45000 lb; 20400 kg
Maximum Digging Depth: 21.1 ft; 6430 mm

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Excavators

322

Net Power - ISO 9249: 129 hp; 96 kW
Operating Weight: 45,700 lb; 20700 kg
Maximum Digging Depth: 20.7 ft; 6310 mm

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321 Hydraulic Excavator

Introducing Next Generation Cat® Excavator 321

321 Medium Excavators

Overview

Versatility at the Lowest Cost Per Hour

Benefits

Performance You Can Feel

Built To Last

Less Downtime. Low Costs.

Features At A Glance

Delivering Excellent Fuel Efficiency

Built To Last

Low Maintenance, More Uptime

Safety First, Always

Simple To Operate

Comfort That Keeps You Going

Smart Fleet Management

Product Specifications for 321

Engine

Weights

Working Ranges and Forces

Hydraulic System

Swing Mechanism

Service Refill Capacities

Dimensions

321 Standard Equipment

NOTE

BOOM, STICKS AND LINKAGE

CAB

CAT TECHNOLOGY

ELECTRICAL SYSTEM

ENGINE

HYDRAULIC SYSTEM

SAFETY AND SECURITY

SERVICE AND MAINTENANCE

UNDERCARRIAGE AND STRUCTURES

321 Optional Equipment

NOTE

BOOM, STICKS AND LINKAGE

CAB

ELECTRICAL SYSTEM

HYDRAULIC SYSTEM

SAFETY AND SECURITY

UNDERCARRIAGE AND STRUCTURES

Product Specifications for 321

Engine

Weights

Working Ranges and Forces

Hydraulic System

Swing Mechanism

Service Refill Capacities

Dimensions

321 Standard Equipment

NOTE

BOOM, STICKS AND LINKAGE

CAB

CAT TECHNOLOGY

ELECTRICAL SYSTEM

ENGINE

HYDRAULIC SYSTEM

SAFETY AND SECURITY

SERVICE AND MAINTENANCE

UNDERCARRIAGE AND STRUCTURES

321 Optional Equipment

NOTE

BOOM, STICKS AND LINKAGE

CAB

ELECTRICAL SYSTEM

HYDRAULIC SYSTEM

SAFETY AND SECURITY

UNDERCARRIAGE AND STRUCTURES

See how 321 compares against frequently compared products.

Tools And Expert Help At Every Turn

Find Dealer

Payment Calculator

Current Offers

Rental Options

Used Options

assignment Product Brochures and More Are Ready to Download!

Caterpillar product brochures and other informational documents are available for your growing business.

Media Gallery

Photos

Product Brochures and More Are Ready to Download!