S-738 Lever Action Grease Gun

Frequently Asked Questions: S-738 Industrial Commercial Lever Action Grease Gun

Why might a lever grease gun develop a grinding feeling when pumping, and how does the S-738 prevent that?

A grinding feeling during pumping on standard lever grease guns is usually caused by one of three failure modes: contaminated grease carrying grit into the pump chamber, a worn plunger seal letting metal particles enter the pump, or a damaged non-return valve seat where the valve has started chattering against a worn seat. The S-738's engineering answers reduce all three: the high-tolerance CNC machined aluminium die cast head holds the pump bore and valve seat tolerance longer than standard-spec cast heads so grinding from valve-seat wear is deferred; the large grease inlet reduces the velocity of grease into the pump chamber, which reduces abrasive wear if the grease is contaminated; and the rolled-thread barrel-to-head joint resists the overpressure leak that commonly develops when back-pressure pushes grit past the thread seal. If grinding does develop on any lever grease gun, the recommended response is to stop pumping, depressurise the gun, unscrew the barrel, inspect the plunger seal and pump chamber for contamination, and flush with mineral spirits before reloading with fresh grease. Industrial-supply distributor support forums and STAR international supplier channels are the correct source for workshop troubleshooting suggestions on persistent issues.

What is the S-738 Industrial/Commercial Lever Action Grease Gun and what makes it different?

The S-738 is STAR's industrial/commercial 10,000 PSI lever grease gun, engineered for day-in-day-out service in demanding environments. Two features define it: a large grease inlet designed to retain prime during use (reducing re-priming frequency across long service cycles), and a high-tolerance CNC machined aluminium die cast head (precision-machined for sustained 10,000 PSI performance at lighter weight than steel-head alternatives). It sits on the same 10,000 PSI platform as the S-709 Heavy Duty but targets different use-cases: the S-709 is optimised for tight-access variable-stroke service, and the S-738 is optimised for high-volume fleet and plant-maintenance routes where prime retention across long greasing cycles matters more than stroke flexibility. The S-738's primary markets are industrial plant maintenance, commercial fleet workshops, amusement-park and roller coaster service, and heavy-equipment dealer workshops.

What does "large grease inlet for prime retention" mean on the S-738?

The grease inlet is the passage between the reservoir and the pump chamber. On a lever grease gun, the pump chamber pulls a fixed volume of grease through the inlet on every stroke. If the inlet is undersized or the follower-spring pressure is insufficient, the pump chamber cannot fill fully, which causes the gun to lose prime, typically at one-quarter-to-one-third-empty fills. The S-738's large inlet is sized to let grease flow into the pump chamber without cavitation even at half-empty reservoir fills when the follower-spring pressure is lower. The result is fewer prime-loss interruptions across a long greasing route, faster re-priming after the rare interruption, and more consistent grease delivery per stroke across the full 500 cc drawdown. For industrial/commercial users that service long multi-point routes across a full shift, the prime retention compounds into measurable productivity gain over the working week.

How does the S-738 compare to the S-709 Heavy Duty and S-711DP Dual Piston?

All three sit on the 10,000+ PSI tier but target different service patterns. The S-709 Heavy Duty shares the CNC machined aluminium die cast head platform at 10,000 PSI but adds a variable-stroke mechanism: full head pressure develops on partial lever strokes, which matters for tight-access fittings (engine bays, pin bushings, inside wheel arches) where a conventional lever can't complete a full stroke. The S-711DP Dual Piston steps up to 12,000 PSI with a dual-piston mechanism that delivers 3X output per stroke, matched to high-volume fleet and large-bearing service where output volume per stroke is the bottleneck. The S-738 is the open-access high-volume industrial/commercial pick: standard 1 g per stroke output, 10,000 PSI, large prime-retention inlet for long greasing routes.

What does "high-tolerance CNC machined aluminium die cast head" mean on the S-738?

The head is produced in two manufacturing stages: first die-cast from aluminium alloy to the rough head shape, then finish-machined on CNC equipment to hold tight tolerances on the pump bore, non-return valve seat, and thread interfaces. Die casting alone gives a usable head but typically with tolerances that degrade quickly under 10,000 PSI cycling; CNC finish-machining holds the valve seat and pump bore within specification across the life of the gun, which is what sustains the 10,000 PSI peak pressure across tens of thousands of pump cycles. Aluminium die cast with CNC precision is the industrial/commercial sweet spot between steel (heavier, more drop-resistant) and standard-spec cast heads (lower precision, shorter valve-seat life). For applications where gun weight matters across extended shifts, the aluminium head is the right construction choice.

Is the S-738 suitable for roller coasters and amusement park ride maintenance?

Yes. Amusement park and roller coaster maintenance is one of the S-738's primary design targets. Ride maintenance involves daily lubrication schedules across multi-point greasing routes (pivot joints, bearings, hydraulic linkages, track rollers, swing bearings, chain drives) where safety-critical reliability depends on consistent grease delivery. The large prime-retention inlet reduces mid-route re-priming interruptions, the 10,000 PSI output covers the typical range of ride-equipment fittings, and the 4-way loading accepts whatever grease-supply format the park's maintenance programme standardises on (cartridge, bulk pail, or depot filler pump). For operators running multiple guns in colour-coded grease-segregation systems (different chemistries on different ride systems), custom colour-coded powder-coat finishes are available via OEM order.

Can the S-738 be used for earth moving equipment and track rollers?

Yes. Earth moving equipment service is a standard S-738 use-case. Excavator pins and bushings, loader articulation joints, bulldozer chassis zerks, track rollers, swing bearings, and construction-site daily service all fit the S-738's engineering profile: 10,000 PSI covers the typical range of earthmoving fittings, the 4-way loading handles bulk-pail service from the site grease pail on remote earth-moving jobs, and the large prime-retention inlet reduces re-priming interruptions across long multi-point chassis-service routines. For severely crusted fittings on mothballed or wet-season-stored equipment where 10,000 PSI is marginal, step up to the S-707 12,000 PSI flagship.

Is 10,000 PSI safe for bearing seals during industrial service?

Yes. Bearing seals typically fail at internal grease-cavity pressures of 500 to 1,500 PSI, far below the 10,000 PSI maximum the S-738 can develop at a fully blocked fitting. Actual pressure reaching the bearing seal depends on the fitting's flow restriction: a clean zerk on a healthy bearing passes grease at low pressure, the pump never reaches maximum PSI unless the fitting is completely blocked. The 10,000 PSI specification is the maximum the pump can build when the coupler is blocked, not the steady-state pressure reaching the bearing. To prevent over-greasing: stop pumping the moment fresh grease appears at the bearing seal or the lever resistance sharply increases. Over-greasing damages seals, causes bearing overheating, attracts contamination, and can cause equipment failure or fire in extreme cases; controlled pumping avoids all of this.

Can the S-738 cause a grease injection injury at 10,000 PSI?

Yes. Grease injection injuries from 10,000 PSI grease guns are documented in emergency medicine and require immediate surgical treatment. A pinhole in the hose or unseated coupler can drive grease through intact skin at 10,000 PSI. The initial wound looks like a tiny puncture and often does not hurt much initially; grease then migrates along tissue planes and causes chemical damage that becomes visible as swelling, colour change, and infection over 24-72 hours. Above 7,000 PSI the likelihood of amputation escalates significantly if treatment is delayed. Go to an emergency department immediately for any suspected injection injury, brief the staff it is a high-pressure grease injection (not a simple puncture), and do not wait for pain to develop. Injection injuries are the primary safety risk on the S-738 and on every 10,000+ PSI grease gun; PPE compliance and hose inspection are the operator-side defences.

What PPE should I wear when using the S-738?

Mandatory: wraparound safety glasses (ANSI Z87.1+ impact-rated with side shields), nitrile chemical-resistant gloves, long sleeves, and closed-toe steel-capped shoes at minimum. Safety rules: never point the coupler or flex hose at any body part or another person, keep the non-lever hand behind the coupler head during pumping, inspect the hose and coupler before each use for visible damage (cracks, bulges, stiffening, loose connections), never test grease flow by pressing the coupler against skin or fabric, never use the gun near open flames (grease is flammable at high temperatures), and do not operate the gun in confined spaces without adequate ventilation. Workshops running colour-coded grease-segregation systems should also verify the grease chemistry on the gun matches the equipment specification before connecting the coupler.

How do I prime the S-738 after a cartridge change?

Retract and lock the plunger rod, unscrew the barrel at the head-to-barrel joint, insert the 14 oz. cartridge nose-first with both seals peeled, screw the head back on, release the plunger rod. Pump the lever 3 to 5 full strokes with the coupler disconnected until grease flows cleanly from the nozzle. The S-738's large grease inlet helps the pump chamber fill on the first strokes without the air-lock that standard lever guns sometimes hit at this step. If priming fails after 5 strokes: check the plunger rod is fully released (the extra-heavy follower spring needs to compress the grease column against the inlet), inspect the cartridge seating for air voids at the cartridge-head interface, and in cold weather allow the grease 5-10 minutes to warm to ambient before priming. First-use priming on a brand-new gun may take 5-8 strokes because the internal cavity is completely empty of grease.

Why is the S-738 easier to re-prime than some lever grease guns?

The large grease inlet is the primary engineering difference. On standard-specification lever grease guns, the inlet is sized for cost rather than for reliable pump-chamber filling; the pump can't pull grease through the restrictive inlet fast enough when the follower-spring pressure drops at partial fills, so the pump chamber fills partially, delivering less grease per stroke and eventually losing prime. The S-738's larger inlet lets grease flow into the pump chamber fully across the full reservoir drawdown, so re-priming after a stuck fitting or a coupler change typically takes 2-3 strokes instead of the 8-10 strokes (or barrel unscrew and repack) that lower-specification guns sometimes need. For industrial/commercial users servicing long greasing routes, the difference is meaningful across the working shift.

Can the S-738 be loaded from a 15 kg bulk pail?

Yes. The 4-way loading supports bulk fill from 5 kg, 15 kg, or 20 kg grease pails. To bulk-fill: retract and lock the plunger rod, unscrew the barrel at the head joint, dip the barrel mouth into the grease pail, and use a scoop to pack grease firmly against the sidewalls to fill the 500 cc reservoir. Industrial/commercial workshops running high-volume greasing routes typically bulk-pack all guns at shift start to minimise mid-shift reload frustration. The S-738's large grease inlet and extra-heavy follower spring handle the bulk-packed grease column pressure across the full reservoir drawdown without the loss-of-prime problems that standard-specification lever guns hit on bulk fills. Bulk fill also reduces per-kilogram grease cost versus cartridge for workshops running multi-gun fleets.

Is the S-738 suitable for cold weather service?

Yes, with one cold-weather operating note. The S-738 operates across -10°C to +80°C ambient, which covers most industrial and commercial service scenarios including winter workshop and fleet-yard conditions. In very cold conditions (below -5°C), grease viscosity increases and all lever grease guns become harder to pump; the S-738 is no exception. Cold-weather recommendations: store the gun and grease cartridges in a heated workshop or service vehicle when not in use, allow grease 5-10 minutes to warm to ambient before high-volume service, and consider switching to low-temperature grease specifications (arctic-rated lithium complex, PAO-based synthetic rated to -30°C) for sustained sub-zero operations. The large prime-retention inlet is particularly valuable in cold weather where standard lever guns are prone to cold-weather prime loss on half-empty reservoirs.

Can the S-738 be colour-coded for grease-segregation systems?

Yes. Custom colour-coded powder-coat finishes are available on the S-738 for OEM and private-label orders. This is a specific industrial/commercial use-case: workshops running grease-chemistry segregation systems (dedicated guns for lithium complex vs calcium sulphonate vs moly-fortified EP vs synthetic chemistries) colour-code the guns to prevent cross-contamination between incompatible grease types. Typical colour codes: blue for moly EP, red for lithium complex, green for calcium sulphonate, yellow for food-grade or light-oil service, with colour-matched flexible hoses and extension sleeves for full-kit visual identification. MOQ 1000 applies for colour-coded orders. Contact the STAR export team for custom colour-code configurations, colour-matched accessories, and workshop grease-segregation system packaging.

What grease types is the S-738 compatible with?

The S-738 is compatible with NLGI 1, 2, and 3 greases across all standard chemistries: lithium complex, calcium sulphonate, aluminium complex, polyurea, moly-fortified EP (extreme pressure), and synthetic PAO-based. For industrial plant machinery and conveyor bearings, NLGI 2 lithium complex or moly-fortified EP is standard. For heavy earth moving equipment (excavator pins, loader bushings), moly-fortified EP or calcium sulphonate handles the shock loading. For amusement park ride bearings, operators typically follow the ride manufacturer's grease specification exactly (varies by manufacturer and ride system). For marine and coastal service, calcium sulphonate or aluminium complex resists water wash-out. Never mix incompatible thickener chemistries in the same gun (lithium + calcium or lithium + polyurea causes hard deposits that clog the non-return valve); for mixed fleets, maintain separate dedicated guns per chemistry, colour-coded for visual identification.

Is the S-738 available for OEM and private-label orders?

Yes. OEM and private-label manufacture is available on the S-738 for global industrial-supply distributors, commercial-fleet tool distribution, and dealer-workshop tool-supply trade. Options include custom branding, packaging design for industrial-supply or commercial retail format, BSPT/NPT/M10 thread variants, custom colour-coded powder-coat finishes, carrying case options, and custom kit configurations per distributor agreement. MOQ 1000 applies as the baseline. Shipping is sea freight to Rotterdam, Hamburg, Antwerp, Felixstowe, Los Angeles, New York, Santos, Jebel Ali, Durban, Mombasa, Lagos, and other industrial-supply hub ports worldwide. Global export destinations include UK, Germany, Italy, France, Scandinavia, Russia, Turkey, Saudi Arabia, UAE Dubai, South Africa, Kenya, Nigeria, Brazil, Mexico, Indonesia, Philippines, Vietnam, Australia, and New Zealand. Contact the STAR export team for distributor pricing, lead times, catalogue requests, and packaging specifications. Made in Ludhiana, Punjab, India, exported to 27+ countries since 1980.