Compare/Allis Chalmers 8550 vs Allis Chalmers HD21

Allis Chalmers 8550 vs Allis Chalmers HD21

Verdict: Allis Chalmers 8550 vs Allis Chalmers HD21

The Allis Chalmers 8550 and the Allis Chalmers HD21 are both tractors — here is how they stack up on the figures that matter. Allis Chalmers 8550 leads on rated power with 254 hp against 225 hp. Allis Chalmers HD21 is the lighter machine (20,638 kg vs 26,400 kg), which helps on soft ground and transport, while the heavier model carries more ballast for traction-limited draft work. Allis Chalmers 8550 holds more fuel (643.5 L vs 511.0 L) for longer stints between fills. Allis Chalmers 8550 is the newer design (1978 vs 1954). In short: choose the Allis Chalmers 8550 for outright pulling power, or the Allis Chalmers HD21 if a tighter budget and lighter footprint matter more. Compare the full spec tables below before booking a demo.

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Acreage600 acBudgetMain crop / use

Fit & specs

Allis Chalmers

Fit score

Clear

Allis Chalmers

Fit score

Best match

Clear

Rated power

254 hp

225 hp

Confidence

40%

Guide price

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Overview

Manufacturer

Allis ChalmersReference

Allis 8550 speeds with 18.4x38 tires.Reference

Drawbar performanceReference

Original price

$86,753Reference

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Steering

hydrostatic powerReference

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Drive

—

crawlerReference

Engine

Fuel tank

643.5 LReference

511.0 LReference

Engine

223.7 kWReference

167.8 kWReference

Drawbar (claimed)

156.6 kWReference

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Drawbar (tested)

162.5 kWReference

100.8 kWReference

Displacement

12.0 LReference

13.8 LReference

Bore/Stroke

133 x 159 mmReference

133 x 165 mmReference

Power

223.7 kWReference

167.8 kWReference

Air cleaner

dryReference

oil bathReference

Compression

16.25:1Reference

13.3:1Reference

Rated RPM

2500Reference

1800Reference

Idle RPM

775-2800Reference

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Firing order

1-5-3-6-2-4Reference

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Starter volts

12Reference

24Reference

Oil capacity

56.8 LReference

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Coolant capacity

68.1 LReference

75.7 LReference

Intake valve clearance

0.381 mmReference

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Exhaust valve clearance

0.508 mmReference

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Power at rated engine speed

189.3 kWReference

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Max power

162.5 kWReference

100.8 kWReference

Transmission

Power DirectorReference

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Gears

20 forward and 4 reverseReference

2 forward and 1 reverseReference

PTO & Hydraulics

PTO (claimed)

186.4 kWReference

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PTO (tested)

189.3 kWReference

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Type

partial power shiftReference

torque converterReference

Valves

3 or 4Reference

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Pump flow

283.5 lpmReference

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Rear Type

IV/IIIReference

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Rear PTO

independentReference

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Rear PTO Type

1000Reference

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Dimensions

Wheelbase

320 cmReference

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Weight

26400 to 27040 poundsReference

20638 kgReference

Front tire

18.4x38Reference

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Rear tire

18.4x38Reference

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Ag front

30.5x32Reference

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Ag rear

30.5x32Reference

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Length

723 cmReference

502 cmReference

Width

303 cmReference

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Ground clearance

43 cmReference

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Front tread

157 to 312 cmReference

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Rear tread

157 to 312 cmReference

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Shipping

11975 kgReference

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Operating

12265 kgReference

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Ballasted

13317 kgReference

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Height

—

251 cmReference

8550 Serial Numbers

1978

1083Reference

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1979

1342Reference

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1980

1553Reference

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1981

1723Reference

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Location:

Front frame, rear left sideReference

Steering clutch housing or instrument panelReference

Electrical

Ground

negativeReference

—

Charging system

alternatorReference

—

Batteries

4Reference

—

Battery volts

12Reference

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Allis Chalmers 8550 Height

Hood

229 cmReference

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Cab

353 cmReference

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Exhaust

391 cmReference

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Test results

Fuel use

66.2 l/hourReference

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Max pull

11893 kgReference

18399 kgReference

Speeds

HD21 Serial Numbers

Fit score weighs budget, operation size, crop match and data confidence against the details above. It’s guidance, not advice — always confirm with a dealer demo.