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Model R21

The ideal residential mower

R21 Model Overview

The R21 is the ideal machine for residential properties. Featuring a powerful 21 HP Kohler KT620 with Smart-Choke technology, this machine is a premium Walker Mower priced for residential owners. Tilt-open seat and tilt-up deck are designed for easy maintenance access.

Type: Non-Collection
Power: 21 HP
Engine: Kohler KT620
Ideal Application: 
Residential Properties
Key Attributes: Agile, Accessible, Compact
Standard Options: 18 x 8.5-10 Turf Tire, Standard Seat

Popular Add-ons:
Comfort Seat
LED Headlight Kit
Mulch Kit
Accelerator Grass Catcher

R21 Video Play Button


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Key Attributes

Key Attributes - Agile


Be Responsive, Be Profitable

Key Attributes - Compact


Get Into and Out of Tight Spots


Fully Synthetic Oil

Kohler Pro 300-Hour Extended Life Oil Equipped

Own An R21

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300 Hours/3YEARSentire tractor
3YEARSor 300 Hours hours on drive system*
LEARN MORE *Gear Axle Assembly, Hydrostatic Transmissions for C, D, T and Hydrostatic Transaxles for B, H, S, R



Bring Home the Model R


Model R Introduction


HOW TO: Model R Deck Tilt-Up


Model R In-Depth


Model R Trailer



Manufacturer: Kohler

Model: KT620

Displacement: 660 cc (40.3 cu. in.)

Max Power: 21 HP @ 3600 RPM

Governed RPM: 3600

Max Torque: 35.9 ft-lbs

Cooling System: Air

Fuel: Gasoline (unleaded - min. 87 octane)

Fuel Capacity: 3 gal (11.36 liter)


Battery: 12V, 300CCA

Charging System: Flywheel Alternator

Charging Output: 18 Amp DC (Regulated)


Manufacturer/Model: Dual Independent Hydro-Gear ZT-2200 Integrated Transaxles

Steering: Hand Lever Control, Individual Wheel

Forward Speed Control: Precision Friction Lock Lever, Cruise Control, with Neutral-Park Position

Parking Brake: Mechanical Cog Lock for each Transaxle (Single Lever Control)

Forward MPH (km/h): 0-6 MPH (0-10 km/h)

Neutral: Transaxle Release by Manual Dump Valve

Blade Drive

PTO Shaft: Single Belt

Blade Drive Clutch and Brake: Electric Clutch [Stops Blades within Five (5) seconds of Disengagement]

Grass Handling

Note: An optional Accelerator® Grass Catcher is available for collection mowing

Grass Catcher Capacity: 31 Gal / 3.3 Bu / 116 L


Recommended Cut Width: Side Discharge: 42 to 48 in. (107 to 122 cm), Mulch: 42 to 48 in. (107 to 122 cm)

Cutting Height: 1.5 to 4 in (4 to 10 cm)

Deck Suspension: Independent Torsion-Flex Frame with Caster Wheels and Counterweight Springs


Drive: 18 x 8.50-10 (Pneumatic 4-Ply, Low Profile)

Tailwheel: 13 x 6.50-6 (Pneumatic 4-Ply)

Deck Caster: 8 x 3.00-4 (Semi-Pneumatic)

Size & Weight


  • Tractor with S48 deck: 96 in (244 cm)
  • Tractor with deck tilted: 74 in (188 cm)
  • Tractor wheel base: 39 in (99 cm)


  • Tractor Only (Outside Tire): 39 in (99 cm)
  • Tractor with S48 deck: 60 in (152.4 cm)


  • Tractor: 42 in (107 cm)


  • Tractor Only: 404 lbs (183 kg)
  • Tractor with S48 deck: 593 lbs (269 kg)



Released Class Model Type Model S/N Range Manual P/N Download
09/22/2022 Model-R R21 Parts 174105 - AND ON 1000-6 PDF
03/22/2022 Model-R R21 Operator's 171697 - AND ON 1000-5 PDF
09/20/2021 Model-R R21 Parts 165963 - 174104 1000-4 PDF
09/14/2020 Model-R R21 Parts 160824 - 165962 1000-2 PDF
09/03/2020 Model-R R21 Operator's 160824 - 171696 1000-3 PDF
09/17/2019 Model-R R21 Operator's 158429 - 160823 1000-1 PDF
08/28/2019 Model-R R21 Parts 158429 - 160823 1000 PDF