Oliver Hart Parr 18-28
Built: 1930–1937 · Series: Other models
Not the right version? The data comes from vehicle registers holding many near-identical versions side by side. Photograph the data plate — we read make and type from it. Open the scanner e-mail address required
Oliver Hart-Parr – further models: the last independent Hart-Parr tractors from Charles City, Iowa, four types from 12-24 E to 28-44, 18.1 to 33 kW from two- to four-cylinder engines
This page gathers Oliver's Hart-Parr tractors outside the named series: the models 12-24 E, 18-27 RC, 18-28 and 28-44. Hart-Parr of Charles City, Iowa, is regarded as a pioneer of the petrol-powered farm tractor in the United States and was absorbed in 1929 into the newly formed Oliver Farm Equipment Company; the last independently developed models continued to be built under the Hart-Parr name into the early 1930s before the brand was fully folded into the Oliver range. The model numbers denote drawbar pull and engine power in the dynamometer nomenclature of the era.
Read on 3 more paragraphs
The register lists 4 versions with 18.1 to 33 kW from two- to four-cylinder engines of 4,599 to 7,260cc, kerb weights from 1,950 to 2,910 kg, lengths from 3,073 to 3,220 mm, widths from 1,549 to 2,032 mm, heights from 1,359 to 1,626 mm and rated speeds from 800 to 1,190 rpm.
As transitional models between the independent Hart-Parr era and the new Oliver range, these tractors reflect the shift in American farm machinery during the interwar years, as slow-revving, large-displacement engines gradually gave way to more compact, faster-turning designs; they ran on kerosene, petroleum or petrol, as was typical of the period.
When buying such pre-war tractors, check the cooling system and valves of the slow-revving, large-displacement engines, fuel system tightness given the multi-fuel operation, and the condition of gears and bearings in the open gearbox; spare parts today are mostly found only through specialist collectors and vintage tractor clubs.
Sources: SpecCodex register, model data: Oliver Hart-Parr (weitere Modelle)
Technical data
Engine
| Fuel | Kerosincorrect |
|---|---|
| Power | 28.4 hp (20.9 kW)correct |
| Rated speed | 1,190 rpmcorrect |
| Cylinders | 4correct |
| Displacement | 4,599 cm³correct |
| Bore | 104.78 mmcorrect |
| Stroke | 133.35 mmcorrect |
| Cooling | water-cooledcorrect |
Dimensions and weights
| Length | 3,220 mmcorrect |
|---|---|
| Width | 1,549 mmcorrect |
| Height | 1,359 mmcorrect |
| Wheelbase | 1,830 mmcorrect |
| Unladen weight | 1,950 kgcorrect |
Drivetrain and chassis
| Drive | rear-wheel drivecorrect |
|---|---|
| Gearbox | 3 V/1 Rcorrect |
| Front tyres | 28" x 5"correct |
| Rear tyres | 44" x 10"correct |
| Top speed | 6.7 km/hcorrect |
Origin and approval
| Construction | frame constructioncorrect |
|---|---|
| Units built | 3,928correct |
Where this model stands
Power-to-weight ratio: 10.7 kW/t (21 kW / 1.9 t)
Power class: Compact (< 40 hp)
Stronger than 16% of the tractors in the register — out of 15,663 models with a stated power figure.
Calculated from the documented figures above — not a rating.
Frequently asked questions
How much power does the Oliver Hart Parr 18-28 have?
The Oliver Hart Parr 18-28 delivers 28.4 hp.
How much does the Oliver Hart Parr 18-28 weigh?
The unladen weight is 1,950 kg.
What engine does the Oliver Hart Parr 18-28 have?
4 cylinders, 4,599 cm³ displacement, Kerosin.
How fast does the Oliver Hart Parr 18-28 go?
Top speed is 6.7 km/h.
What are the dimensions of the Oliver Hart Parr 18-28?
3,220 mm × 1,549 mm × 1,359 mm.
When was the Oliver Hart Parr 18-28 built?
Production years: 1930–1937.
What to check before buying
- Check the hour meter against the service records — a replaced instrument is the most common gap.
- Compare the data plate and chassis number with the papers.
- Check the weights in the papers against the figures here — attachments change them.
- Check front and rear tyre sizes: mismatched pairs strain the drivetrain.
- Shift the gearbox cold and warm — jumps only show up at temperature.
- Load the hydraulics and watch for sag.
- Ask about parts availability for this build year — the running costs hang on it.
A general list for this type of machine — no substitute for an inspection or an appraiser.
We do not sell machines. We ask the dealers who carry this model and come back with price and lead time.
Request a quote →
We ask the suppliers and come back with price and lead time.
Request spare parts →
This page carries 21 individual figures for this model. They come from 1 recorded source; every figure can be traced there. What we cannot document is not here — we leave gaps open rather than estimate them.
Missing a figure you were looking for? Report it →
Know this machine better? Have a photo, a manual, or know that a figure is wrong? Add it to the register →
Other models in this series
Sources: Wikibooks Traktorenlexikon (CC BY-SA 4.0) (retrieved August 2026) · Values adopted and presented in our own form; changes from the source are possible. · How we check the data
Tractor in 3D section
Turn the model, look inside and click an assembly — each one is explained.
