Air over oil intensifiers provide an on-demand, localized power boost by converting shop air to higher hydraulic pressure. They are ideal for small hydraulic devices that do not need high-volume fluid displacement, like hydraulic brakes or vises.
How Does an Intensifier Work?
An air over oil intensifier is a compact, self-contained unit and it has two chambers: one for air and one for hydraulic fluid.
The compressed air, which typically ranges between 80 to 100 psi, drives a piston in the first chamber, which pressurizes a small reservoir of hydraulic fluid or oil in the second chamber to create the required stopping force.
Intensifiers work with both standard and spring-applied hydraulic brakes.
How Much Boost Can You Achieve?
The ratio of pressure increase reflects the area of the two piston surfaces. In a 10:1 intensifier, for example, the surface of the pneumatic piston is ten times greater than that of the hydraulic piston. Fluid displacement is inversely related to pressure increase.
Branham air over oil intensifiers are designed with conversion ratios from 5:1 to 36:1. Depending on the model you choose, the intensifier will boost your available power by 500% to 3600%. That lets you choose the most appropriate brake for the task, whether or not a hydraulic system is available.
Branham also makes OVLBOOST®, an all-in-one pneumatic-to-hydraulic intensifier. It uses a unique oval piston and bore, giving it a low profile that can be mounted flat or on its side.
Multiple intensifiers can be used in tandem if greater fluid displacement is needed. Doubling up intensifiers still uses a single pneumatic stroke, but doubles the fluid displacement and the force generated.
To achieve over 10 cubic inches of displacement, for example, you could use two intensifiers that each produce 7.068 cubic inches.
There is a practical limit to this approach, and multiple intensifiers can also be used in parallel for sequencing applications.
What are Common Applications for Air Over Oil Intensifiers?
While often used for braking, intensifiers show up in many industrial settings wherever a small hydraulic device needs more force than shop air alone can provide.
Winding and tensioning. Web, wire, and coil winding machines rely on steady, controllable tension. An intensifier delivers the hydraulic pressure needed to maintain that tension without a dedicated hydraulic power unit.
Robotics and indexing. Grippers and indexing tables need high, steady clamping pressure to hold a part still while tools perform their work. On CNC trunnion tables, for instance, an intensifier eliminates the risk of movement during machining.
Heavy-duty and outdoor equipment. Wind turbines, agricultural equipment, and mining operations often run on compressed air in the field. An 18:1 intensifier, Branham's largest volume displacement traditional model, can supply the braking torque these applications require without adding a hydraulic system to the equipment.
Transportation and amusement equipment. Railroad cars and amusement park rides use brakes for holding, slowing, and stopping. For holding, spring-applied hydraulic brakes paired with an intensifier and the vehicle's existing pneumatics create an efficient hydraulic e-brake.
Clamping and holding. The high pressure an intensifier generates makes it well suited to clamping and holding applications on manufacturing and assembly lines.
Testing and calibration. Testing and calibration equipment often needs precise, controlled hydraulic pressure to evaluate the performance of other hydraulic systems or components. Intensifiers supply that pressure without a full hydraulic loop.
Safety and emergency systems. Some safety and emergency braking systems call for a rapid hydraulic response. An intensifier's on-demand, self-contained design fits that requirement well.
How Do You Size an Air Over Oil Intensifier?
Proper sizing balances two factors that move in opposite directions: pressure amplification and fluid displacement. A higher ratio produces more pressure but displaces less fluid per stroke.
Step 1: Calculate the Fluid Displacement You Need
Find the piston diameter and stroke length of the device the intensifier will drive, then apply this formula:
Displacement volume = π × (piston radius)² × stroke length
Example: A hydraulic brake has a 1-inch piston diameter (0.5-inch radius) and a 0.25-inch stroke.
- Displacement per piston: 0.196 cubic inches
- Total for a two-piston brake: 0.392 cubic inches
Match that number against what each model delivers per stroke:
- INT05, INT10, INT20: 0.44 to 0.50 cubic inches
- INT09, INT18, INT36: 1.77 to 7.068 cubic inches
Either an INT05 or INT10 would cover the example above.
Step 2: Match the Pressure Requirement to a Ratio
Get the minimum required hydraulic pressure from the brake manufacturer's specifications, then divide it by your available shop air pressure to find the minimum ratio needed. Always round up to the next available ratio.
At 100 psi shop air:
- 5:1 → 500 psi
- 10:1 → 1,000 psi
- 18:1 → 1,800 psi
- 20:1 → 2,000 psi
- 36:1 → 3,600 psi
Example: A brake that requires 1,500 psi needs at least an 18:1 ratio for a safety margin.
Choosing Between OVLBOOST and the Traditional INT Series
OVLBOOST fits when:
- Space is limited (low-profile, oval piston design)
- Output needs fall in the 500 to 780 psi range (7.8:1 ratio at 100 psi shop air)
- Displacement needs are modest (0.460 or 0.920 cubic inches, depending on stroke length)
A higher-ratio INT model fits when:
- The application is a spring-applied hydraulic brake requiring 1,500 to 3,000 psi to release (INT18 or INT36)
- Shop air runs below 100 psi, since a higher ratio compensates for the lower starting pressure
Common Sizing Mistakes
- Assuming 100 psi. Base calculations on your facility's actual shop air pressure, which may run at 80 or 90 psi.
- Missing pistons. Include every piston in the brake or device when calculating total displacement.
- Mismatching brake type. INT05, INT10, and INT20 lack the volume that spring-applied brakes require. Confirm compatibility before specifying a small intensifier for that application.
Using Multiple Intensifiers
If a single intensifier cannot meet your fluid displacement needs, multiple units can run in parallel off the same pneumatic supply. Beyond three or four units, a custom-designed intensifier usually works better.
How Does an Air Over Oil Intensifier Differ from a Full Hydraulic System?
An air over oil intensifier replaces a full hydraulic system with a single self-contained unit mounted in line with the pneumatic actuator. A full hydraulic system needs a power unit, a reservoir, a dedicated motor and pump, and the piping to connect it all to the point of use.
That difference matters in three ways:
- Cost drops, since there is no power unit or motor to purchase and maintain.
- Footprint shrinks, since the intensifier occupies a fraction of the space a hydraulic system requires.
- Maintenance simplifies, since there is no large fluid reservoir to monitor and no risk of hydraulic leakage spreading through the facility.
For scale, an intensifier is built for small, localized hydraulic devices like brakes, grippers, and clamps that do not need high-volume fluid displacement.
Applications that require continuous high-volume hydraulic flow still call for a full system. For everything in between, an intensifier delivers hydraulic force exactly where it is needed, using the shop air already running through the facility.
Get the Full Story
Air over oil intensifiers are simple and reliable, delivering the power and stability needed to precisely control braking, tensioning, or stop-and-hold. Their space-saving design mounts right in line with the pneumatic actuator, and their cost stays low since there is no hydraulic system to maintain.
Sizing one correctly comes down to two numbers: the fluid displacement your device needs and the pressure ratio that gets you there. Get those right, and an intensifier gives you hydraulic-level force without installing a hydraulic system.
If your application falls outside a standard ratio or displacement range, a custom-designed intensifier can be built to fit.
