Hart-Parr 28-50

Last Updated: July 2024

Overview

The Hart-Parr 28-50 is a classic standard-tread utility tractor with a robust 4-cylinder liquid-cooled gasoline engine. It features a 675.1 cubic inch displacement, horizontal cylinder orientation, and valve-in-head configuration. The engine is rated at 50.55 hp and 850 RPM. The 2WD chassis has manual steering, and the gear transmission offers 2 forward gears and 1 reverse gear. Steel tires measure 28x7 inches (front) and 51x14 inches (rear). Independent testing revealed an operating weight of 10,394 lbs, engine compression of 70 psi at rated RPM, and oil consumption of 15.75 gallons during the complete test.

Key Specifications

Category: Utility, Standard Tread

Transmission: Gear

Drive Type: 2WD

Operating Weight: 10394

Fuel Type: Gasoline

Hart-Parr 28-50 vs. Similar Tractors

Operating Weight

Average

Greater than 59% of similar tractors.

Technical Specifications

Engine

Manufacturer: Hart-Parr
Model: -
Cooling Type: Liquid-cooled
Cylinder Orientation: -
Valve Configuration: -
Fuel Type: Gasoline
Induction Type: Naturally aspirated
Cylinders: 4
Displacement (ci): 675.1
Bore (in): 5.75
Stroke (in): 6.5
Rated RPM: 850
Power Output (hp): -

Transmission

Type: Gear
Forward Gears: 2
Reverse Gears: 1
Total Gears: -

Dimensions

Length (in): -
Width (in): -
Height (in): -
Operating Weight (lb): 10394

Power Take-Off (PTO)

PTO Type: -
PTO Speed 1 (rpm): -
PTO Speed 2 (rpm): -
PTO Speed 3 (rpm): -

Miscellaneous

Chassis: 4x2 2WD
Drive Type: 2WD
Steering Type: Manual
Coolant Capacity (qts): -
Front Tire Diameter (in): 28
Front Tire Width (in): 7
Rear Tire Diameter (in): 51
Rear Tire Width (in): 14
Front/Rear Rim Diameter (in): -
Tire Type: Steel
Manufacture - End Year: -
Hitch Type: -
Hitch Category: -
Hitch Position: -
Hitch Capacity (lb): -
Operator Station Type: -
Starter Type: -
Brake Type: -
Hydraulic System Type: -

Test Results

Nebraska Tractor Test Laboratory - Test Date: August 17 to 31, 1927

Maximum Power and Fuel Consumption

Maximum Brake Horsepower (BHP): 50.55 HP at 855 rpm
Fuel Consumption at Maximum Power: 4.694 gal/hr of distillate with a fuel efficiency of 10.73 HP.hr/gal

Drawbar Performance

Power at Rated Engine Speed: 26.52 HP with a drawbar pull of 2967 lbs and a speed of 3.60 mph at 855 rpm
Fuel Consumption at Drawbar Power: 4.790 gal/hr of distillate

Torque and Engine Performance

Maximum Torque: Engine torque was not explicitly specified but compression was noted at 70 lbs per sq. in at 850 rpm
Varying Load Test (Torque Rise): Showed a significant power variation with an identifiable lowest power at 10 HP and maximum at 51.49 HP

Hydraulic Performance

Oil Consumption: During the complete test, 15.75 gallons of Mobil oil were used for the engine

Overall Efficiency

General Observations: The tractor was found to have mechanical issues, specifically with cylinder compression, during post-test inspections but showed no undue wear otherwise

NTTL.(1927).Nebraska OECD Tractor test 140 for Hart-Parr 28-50. Lincoln, NE:Nebraska Tractor Test Laboratory. Retrieved from https://digitalcommons.unl.edu/tractormuseumlit/760