What a pneumatic grease dispenser is
A pneumatic grease dispenser is a reservoir-fed dispensing station built around an air motor, a grease piston, a reservoir, and a delivery hose ending in a nozzle or coupler. Connect a compressed-air line and it pushes grease continuously for bearing service, chassis points, and fleet maintenance: the installed-station counterpart to the handheld pneumatic grease gun.
The distinction matters. A grease gun is a handheld trigger tool that serves one fitting at a time from a small tube or cartridge. This unit carries its own grease supply, runs through a full shift without reloading, and suits continuous, high-volume greasing. See our grease pump overview for where this unit sits in the range, then compare the declared specifications below.
Declared specifications
| Item | Declared specification |
|---|---|
| Pressure ratio | 50:1, 60:1, or 65:1, model dependent |
| Output pressure | up to 350-600 bar, model dependent |
| Air supply, operating | 4-8 bar |
| Air supply, minimum to start | from 2 bar |
| Air consumption | about 200-400 NL/min at full cycle rate |
| Air inlet | 1/4 inch or 3/8 inch BSP |
| Grease outlet | 1/4 inch BSP female |
| Free-flow output | 600-1000 g/min |
| Delivery per stroke | about 2-4 g per stroke at 50:1 |
| Grease consistency | NLGI 3 down to semi-fluid grades |
| Max grease viscosity | up to 100000 cSt |
| Operating temperature | -10°C to +60°C |
| Reservoir | 13/20/30 kg portable; 50-200 L drum-mounted |
| Follower plate | with NBR seal standard; FKM optional |
| Pump body | hardened steel or cast iron |
| Delivery hose | 2/3/4 m |
| Weight without grease | 6-18 kg |
| Check valves | ball or poppet |
| Reversing valve | air-distribution valve, pilot-operated |
How the air drive builds pressure
The air motor piston and the grease piston have different face areas, and the ratio between them is the pressure ratio. A 50:1 pump fed with 8 bar shop air delivers about 400 bar at the grease outlet. Higher ratios raise output proportionally, so a 60:1 or 65:1 pump on the same supply sits at a proportionally higher ceiling.
A pilot-operated reversing valve shuttles air across the drive piston, and ball or poppet check valves on the grease side open and close with each stroke to pull grease into the chamber and push it out to the hose. The follower plate rides on top of the grease in the reservoir, tracking the level down, keeping grease over the pump inlet, and limiting the air space above the grease.
Keep two numbers separate. The 350-600 bar output figure is blocked-nozzle pressure, measured with the outlet deadheaded; the 600-1000 g/min free-flow figure describes delivery speed at low back-pressure. A high blocked-nozzle number does not by itself fill a fitting faster.
What your compressor must supply
At full cycle rate the dispenser draws about 200-400 NL/min. A small workshop compressor can feed it intermittently, but continuous production greasing needs enough receiver volume for pressure to stay inside the 4-8 bar operating band between cycles.
Receiver sizing stays qualitative on purpose: match compressor flow and receiver volume to your measured duty cycle. If line pressure sags during long runs, the air side is undersized for that duty. Fit a filter and regulator ahead of the 1/4 inch or 3/8 inch BSP inlet, drain condensate from the line, and see our air grease pump overview for the wider range.
Dispenser, handheld gun, or pressure-class pump
Neighbouring products solve different problems. A pneumatic grease gun engineering guide describes a handheld trigger tool that serves one fitting at a time from a small tube; this dispenser is a reservoir-fed station built for continuous duty, and the two are not interchangeable on a specification sheet.
On pressure class, heavy-duty grease pumps serve fixed high-pressure centralized supply, while a low-pressure grease pump covers machinery that does not need the 350-600 bar class. Choose the class that matches your fittings and couplers rather than defaulting to the highest figure.
Care and troubleshooting
Pressure that fades over time usually traces to one of three internal causes: check valves worn enough to let grease slip back, a follower plate that no longer seats on the grease and lets air get to the inlet, or piston seals passing grease internally. All three show the same external pattern: the motor cycles normally while outlet pressure sags.
If the motor runs but no grease moves at all, the pump is likely not priming. Stiff grease, an air pocket above the grease, or a dry pump chamber all block prime. Run the unit on slow cycles at 2-3 bar with the outlet unrestricted until grease flows steadily, then return to working pressure.
Cold thickens grease: an NLGI 3 grease that pumps easily at workshop temperature can stiffen below about 5°C, so confirm the grease grade for your equipment before blaming the pump. Clean every fitting before coupling, because the coupler is the most abused part of the circuit and debris pushed through it lands in the bearing. Use delivery hose rated above the pump output, and inspect hose and coupler regularly. Our grease line tubing and fittings selection guide covers sizing in more detail. If pressure still sags after these checks, contact our application team before opening the pump.
Frequently Asked Questions
What compressor do I need to run a pneumatic grease dispenser?
Plan for about 200-400 NL/min air consumption at full cycle rate within a 4-8 bar supply. Size the receiver to your duty cycle so pressure holds between cycles.
Why does output pressure drop over time?
Most cases trace to worn ball or poppet check valves, a follower plate that no longer seats, or piston seals bypassing internally. The motor sounds normal while outlet pressure sags, which signals internal slip rather than an air-supply problem.
What is the stiffest grease it will pump?
NLGI 3 is the stiffest declared grade, with semi-fluid grades at the soft end. NLGI 3 can stiffen below about 5°C, so confirm the grease grade for your equipment.
Can I run synthetic or specialty greases?
Often yes, but the seal must match the grease chemistry. For synthetic or specialty greases, confirm seal compatibility with us before ordering.
How do I choose a pressure ratio?
Divide the pressure your application needs by your available shop air pressure; the result points to the smallest suitable ratio. Leave a margin above that figure instead of running at the limit.
How do I control dispensed volume on an automated line?
Add a metering outlet and let a timer or machine controller trigger the strokes; each stroke then delivers a repeatable shot volume. The metering valve on the outlet line sets the dose per cycle.
Why does the motor run without building pressure?
Usually the pump is not priming: stiff grease, an air pocket above the grease, or a dry chamber blocks suction. Run slow cycles at 2-3 bar with the outlet open until grease flows steadily.
What routine care does the dispenser need?
Keep the reservoir closed, the air supply dry and filtered, and fittings clean before every coupling. Inspect the hose, coupler, and check valves at regular intervals, and confirm parts with us.
Where do I get help choosing a unit?
Start at our contact page with your grease, duty, and fittings, and we will help match ratio, reservoir, and hose. The same details sent by email work just as well.
Who builds and supports this dispenser?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, builds and supports every unit. Email inquiry@isohitech.com for specifications and a quotation.
