What makes a compressor towable
A towable compressor combines three things: the compressor package (airend, engine or motor, cooling, controls and canopy), the running gear (axle, wheels, suspension, brakes and lights where fitted) and the towing connection (drawbar, towing eye or ball coupling, jockey wheel and parking stand).
Wheels and a drawbar make a machine movable. They do not by themselves make it suitable for any particular towing vehicle, road or terrain. Running-gear options differ between models and even between variants of one model: fixed or adjustable drawbars, single or tandem axles, braked or unbraked, site-tow or road-tow configurations. Always confirm the configuration of the actual machine offered.
Most towables are diesel driven, so they work where there is no site power. Electric towables exist for sites with a supply and for noise- or emissions-sensitive work. See diesel portable compressors and electric portable compressors.
Sizing a towable compressor by job
Size by the air your tools need at the pressure they need, plus hose losses and a margin, not by the largest machine available.
| Class | Typical flow | Typical pressure | Common work |
|---|---|---|---|
| Compact | 100–185 cfm | 7 bar (101.5 psig) | One breaker or chipping hammer, small tools, maintenance |
| Small | 185–250 cfm (about 5.2–7.1 m³/min) | 7 bar (101.5 psig), some 10 bar | One or two breakers, small rock drill, small blasting nozzle |
| Medium | 250–400 cfm (about 7.1–11.3 m³/min) | 7–10 bar (101.5–145 psig) | Two to four breakers, rock drills, one No. 5 blasting nozzle, standby plant air |
| Large | 400–600 cfm (about 11.3–17 m³/min) | 7–14 bar (101.5–203.1 psig) | Crawler drills, quarry drilling, one No. 6–7 blasting nozzle, pipeline support |
Typical tool demands at about 7 bar (101.5 psig): a breaker or rock drill 85–145 cfm; a chipping hammer depends on its size and model (see maker’s data); a No. 6 blast nozzle 280–300 cfm. Remember that every extra bar of pressure costs about 7% more power, so do not order 14 bar if the work needs 7. Borewell and DTH drilling, at 600–1,500 cfm and 200–400 psig (13.8–27.6 bar), is normally done with larger truck or skid-mounted packages.
Write a movement brief before comparing offers
The question is not just “how far is the site?” but how the machine will travel from our yard or yours to its final working position.
| Movement item | What to establish |
|---|---|
| Moves within the site | Route, ground conditions, slopes, how often the unit will be repositioned |
| Travel between sites | Whether the unit will be towed on public roads or carried on a truck, and who is responsible for the transport assessment |
| Towing vehicle | Vehicle type, hitch and coupling, towing capacity against the compressor’s gross weight |
| Destination access | Gate widths, turning space, soft ground, overhead lines |
| Parking position | Level ground, distance from excavations, cooling-air clearance |
For longer transfers, many contractors carry towable compressors on a truck or low-bed trailer rather than towing them. That avoids running gear wear and road-tow requirements on rough routes. Local rules for towing on public roads must be checked for the specific vehicle and machine.
Pre-tow checks
- Engine off, air system depressurised and the service valves closed.
- Canopy doors closed and latched; loose hoses and tools removed or secured.
- Coupling correctly engaged and locked; safety chain or breakaway cable attached where fitted.
- Drawbar height set so the machine tows level, if adjustable.
- Jockey wheel and parking stands raised and secured.
- Tyres inflated to the maker’s pressure, wheel nuts tight, no visible damage.
- Brakes, where fitted, released and tested; lights and indicators working if road-towed.
- Towing speed and route suited to the running gear and the ground.
Parking and setting up at the work position
- Park on firm, level ground; the oil level sight glass and separator tank are designed to be read level.
- Apply the parking brake and chock the wheels on any slope.
- Keep the unit back from trench edges and excavations.
- Point the cooling-air discharge and engine exhaust away from workers, buildings and the cooling-air inlet.
- Avoid tucking the machine against a wall or under a low roof, which causes hot-air recirculation.
- Lay out hoses to avoid kinks and vehicle traffic; use whip checks on couplings.
In Indian summer heat of 40–45 °C, and above 45 °C on open sites, setting up in shade with free airflow makes a real difference. A normal oil-injected screw runs at a discharge temperature of about 75–95 °C; recirculation and dusty coolers push it towards a high-temperature shutdown.
Safety features to check before you buy or hire
- Automatic shutdowns for high discharge temperature, low engine oil pressure and high coolant temperature.
- A pressure safety valve rated for the machine.
- Emergency stop accessible from outside the canopy.
- Spark arrestor where the site requires one, for example near fuel installations.
- Fluid containment in the chassis to catch oil, fuel and coolant leaks.
- Clear lifting points if the unit will also be craned.
Running gear maintenance
The running gear is often the most neglected part of a towable compressor. Site use exposes it to potholes, mud and long idle periods.
- Check tyres, wheel nuts and wheel bearings at regular intervals; grease bearings to the maker’s schedule.
- Inspect the drawbar, towing eye, coupling and mountings for cracks, wear and loose bolts.
- Check brake adjustment and linkages where brakes are fitted.
- Check the jockey wheel and parking stands.
- Test lights and wiring if the unit is road-towed.
The compressor and engine service runs alongside this. On our own hire jobs we change oil and service every 300 running hours. See portable compressor service for full details.
Hoses, couplings and accessories
A towable compressor is only as useful as the air that reaches the tool. Undersized or very long hoses cause pressure drop, so a machine set at 7 bar (101.5 psig) may deliver noticeably less at a breaker 60 metres away. Plan the hose kit with the machine.
- Choose hose bore for the flow and length; larger bore for long runs and high-flow tools.
- Use couplings rated for the working pressure, with whip checks or safety clips on every joint.
- Fit a line lubricator for percussive tools where the tool maker requires it.
- Add an aftercooler and moisture separator for blasting, painting and cable blowing.
- Carry a manifold where several tools work from one machine.
Store hoses coiled, off the ground and away from sun and oil when not in use, and condemn any hose with cuts, bulges or exposed reinforcement.
Buy, hire or used
For steady year-round use at one pressure band, owning a towable compressor usually makes sense. For short projects, seasonal peaks, unusual pressures or breakdown cover, hiring avoids an idle asset. A good used machine with a known service history is a sensible middle path for many contractors. Whichever route you take, compare whole packages: flow and pressure, hoses and treatment equipment, running gear, service support and spares availability.
How Reddy Compressors helps
Reddy Compressors sells new and used towable compressors, rents them from our own fleet and services and supplies spares for ELGi, Atlas Copco, Ingersoll Rand, KAESER, Chicago Pneumatic, Doosan and other makes. We are an independent multi-brand specialist, not an authorised dealer. We have tie-ups with all major and reputed brands. We work from Tarnaka, Secunderabad, with more than 20 service engineers and technicians covering Telangana and Andhra Pradesh, and we supply machines and spares across India.
- Sizing by tools, pressure and hose run.
- Rental from 50 to 2,000 cfm and 2–30 bar, diesel and electric, with hoses, aftercoolers and separators where needed, through our rental service.
- Operators available for hire jobs.
- Service, AMC and breakdown repair, including running gear.
- Spares identified from the nameplate and serial number, with fit confirmed before quoting.
Our team has supplied 400 cfm and 450 cfm compressors on hire for steel-plant, power-plant, lift-irrigation and infrastructure projects.
What to send us
- The tools or application, with the number of tools working at once.
- Required pressure in bar or psig and hose length.
- How the unit will be moved: site towing, road towing or carried on a truck.
- Site location, ground conditions and expected duration.
- For service or spares: make, model, serial number and nameplate photographs.
Frequently asked questions
What size towable compressor do I need for a jackhammer?
A typical breaker needs about 85–145 cfm at 7 bar (101.5 psig), depending on its size. One breaker runs on a compact 100–185 cfm machine; two need a 185–250 cfm class; three or four need 250–400 cfm. Allow for hose losses and wear, and check the tool maker’s air consumption figure. Oversizing wastes fuel, so match the machine to the tools.
Can a towable air compressor be towed on public roads?
Only if the specific machine’s running gear is designed and equipped for road towing and the towing vehicle and journey meet the applicable rules. Many site units are intended for towing within a site only. For longer journeys contractors often carry the compressor on a truck. Check the running-gear configuration of the exact unit before planning road movement.
What checks should I do before towing a portable compressor?
Stop the engine and release air pressure, close and latch the canopy, secure hoses, lock the coupling and attach any safety chain, raise the jockey wheel and stands, check tyres and wheel nuts, release and test brakes where fitted, and test lights if road towing. Choose a speed and route suited to the running gear and ground conditions.
Is it better to hire or buy a towable compressor?
Buying suits steady year-round work at one pressure band. Hiring suits short projects, peak demand, unusual pressures and breakdown cover, because you avoid an idle asset and maintenance burden. A used machine with a documented service history is a cost-effective middle option. We sell new and used units and rent from our own fleet, so we can advise on either route.
How often should a towable diesel compressor be serviced?
Follow the engine and compressor makers’ schedules, shortened for dusty sites and high ambient temperatures. On our hire jobs we change oil and service every 300 running hours. Do not forget the running gear: wheel bearings, tyres, drawbar, coupling and brakes need regular inspection, because site potholes and long idle periods wear them out without warning.
Why does my towable compressor shut down on hot afternoons?
Most often the cooling system cannot reject heat: dusty radiator or oil-cooler fins, hot air recirculating from a wall or another machine, low oil level or a faulty thermostatic valve. The high discharge temperature shutdown is protecting the airend. Clean the coolers, reposition the unit with free airflow and shade, and check the oil before restarting.
Related pages
Calculators and worked examples
These tools give indicative figures for screening, comparison and for preparing an enquiry. They run in your browser and send nothing. No prices or tariffs are assumed: enter your own to see costs. Efficiencies and other figures shown are example values: replace them with your own. Results are not a performance guarantee or a design certificate; final selection is confirmed by a service engineer against the machine data sheet and the site.
Compressed air demand estimate
Add up the air your tools and processes use, apply duty and simultaneity, then add leakage and growth allowances to reach a capacity to enquire about.
The worked example below shows the method with fixed numbers. Turn on JavaScript to change the inputs.
Worked example
Inputs
- Unit for the air each tool uses: L/s
- Group A: number of tools: 6
- Group A: free air each (in the unit above): 4
- Group A: duty (%): 40
- Group B: number of tools: 2
- Group B: free air each (in the unit above): 15
- Group B: duty (%): 60
- Group C: number of tools: 1
- Group C: free air each (in the unit above): 40
- Group C: duty (%): 80
- Simultaneity of all tools (%): 65
- Leakage allowance (%): 15
- Growth allowance (%): 10
Result
- Connected demand: 94 L/s = 199 cfm
- Average demand (duty-weighted): 59.6 L/s = 126 cfm
- Simultaneous peak: 61.1 L/s = 129 cfm
- Design basis (higher of average and peak): 61.1 L/s = 129 cfm
- Design capacity with allowances: 77.29 L/s = 4.64 m³/min = 163.8 cfm
Method. Average demand = Σ(number × air per tool × duty). Peak = Σ(number × air per tool) × simultaneity. The peak can never be lower than the average, so the design basis is the higher of the two. Design capacity = design basis × (1 + leakage) × (1 + growth).
What to take from it. Leakage and growth allowances move the answer as much as any single tool. Where you can, replace catalogue figures with measured ones.
Technical content reviewed by D. Srinivas Reddy, Managing Partner and service engineer, Reddy Compressors. Last updated 17 October 2026. How our engineering content is reviewed.