S-724 Lever Action Grease Gun

Frequently Asked Questions: Lever Action Grease Gun

What features matter most in a high capacity lever action grease gun?

Four features decide whether a high-capacity lever gun performs in fleet-service use: head material, pressure rating, capacity per fill and loading flexibility. On the S-724: drop-resistant forged steel head with Quadra-Cut Precision machining, 12,000 PSI (830 bar) maximum working pressure, 750 cc (24 oz.) extended-barrel reservoir that covers 35-40 fittings per fill, and 4-way loading accepting 14 oz. (400 g) cartridges, bulk-pack pail grease, suction fill or filler pump. The combination targets fleet-service routes where both high pressure and high capacity matter on the same shift.

What PSI do I need for heavy duty applications?

12,000 PSI (830 bar) is the maximum tier for handheld lever action grease guns and the S-724 delivers it. For typical automotive and agricultural service, 6,000-8,000 PSI is enough to seat grease in open zerks. For heavy-duty fleet service, construction excavator pins, mining equipment and industrial sealed bearings where fittings may be crusted, corroded or tightly packed, the full 12,000 PSI of the S-724 is the margin that breaks through resistant fittings. The 12,000 PSI rating is the working pressure, not the burst pressure. The gun is designed to operate continuously at that level through the Quadra-Cut Precision steel head.

How much grease does the S-724 output per stroke?

The S-724 outputs 1 gram per stroke, or 1 ounce per 28 strokes. A full 750 cc (24 oz.) fill delivers approximately 672 grams through 672 strokes before needing a reload. The 40:1 mechanical advantage of the lever compounds that 1 gram per stroke into 12,000 PSI at the coupler. For typical service planning: a 20-gram fitting shot needs 20 lever strokes, a 35-40-fitting machine needs 700-800 strokes, a 750 cc reservoir covers one full heavy machine or 2-3 smaller machines on one fill. Stroke-count planning is easier on the S-724 than on variable-stroke guns because output per stroke is constant across the full 750 cc reservoir.

Is 4-way loading better than 3-way loading?

Yes for fleet-service flexibility. The S-724 supports 4-way loading. 14 oz. (400 g) cartridge (fastest, cleanest workshop reload). Next, bulk fill from 5 kg, 15 kg or 18 kg pails (most economical for high-volume operations). Then, suction fill from open containers (useful for specialty greases only available in open packaging). After that, filler pump fill through a grease dispenser bucket or S-918 filler connector (fastest for multi-gun fleet workshops). 3-way loading omits the filler-pump option. For fleet depots running multiple guns off a central bulk container, 4-way is the efficiency-multiplier feature.

How do I prime the S-724 extended barrel grease gun?

Prime the S-724 in four steps after every reload. Ensure the head is screwed down snug against the barrel. Next, crack the head a quarter turn to open the bleed path. Then, pump the lever through five to eight full strokes to purge air from the 750 cc reservoir. After that, retighten the head once grease flows without air bubbles. The extended barrel needs 5-8 priming strokes versus 3-5 on standard 500 cc guns because the reservoir has more internal volume for air to occupy during reload. Never prime against a connected fitting . Prime with the coupler disconnected so air escapes at the head, not into a bearing.

What grease gun do you recommend for farm and ranch tractor service?

For tractor service with 20-30 grease points per machine including implements, the S-724 covers one full tractor plus partial implement service per 750 cc fill. The 14 oz. cartridge compatibility matches standard farm-supply cartridge stocking. The 12,000 PSI pressure breaks through hard-to-seat pins on implements left outdoors. The drop-resistant steel head survives being thrown in utility beds between paddocks. For smaller tractors with under 15 fittings, the 500 cc S-707 is sized right. For large farm equipment with 50+ fittings (large combines, irrigation pivots), consider the 1000 cc S-732.

Can I use the S-724 for front end loader pins and construction equipment?

Yes. Construction equipment service is a primary S-724 application because it combines four S-724 strengths: 12,000 PSI for crusted pins, 750 cc capacity for 40-60-fitting machines, drop-resistant steel head for job-site handling, and 4-way loading for depot-to-field flexibility. Front end loader pin service typically runs 15-25 grease points per machine. The S-724 covers 2-3 loaders per fill. For excavator boom and stick pins with heavier grease loads (35-50 fittings per machine), plan on 1-2 machines per fill. The drop-resistant steel head is the feature that separates the S-724 from aluminium-head alternatives in this application. Construction yards drop tools routinely.

Die cast head vs steel head ; which lasts longer?

Both are engineered for long service life but favour different environments. The S-724's drop-resistant forged steel head with Quadra-Cut Precision Technology outlasts aluminium heads in drop-heavy environments (construction, mining, agricultural field service) because steel absorbs impact without cracking. The aluminium die cast head on the S-724DC outlasts steel in humid and coastal environments because aluminium naturally resists corrosion where steel needs protective coatings. Both heads on STAR flagship guns are rated for 10+ years of daily workshop service when maintained correctly. The choice is service-environment, not longevity.

What causes air lock in the S-724 and how do I eliminate it?

Air lock happens when an air pocket forms above the grease column and the follower spring cannot compress air to build pressure through the non-return valve. Four common causes on 750 cc extended-barrel guns. Incomplete bulk-fill packing leaving voids in the longer reservoir. Next, swapping cartridges mid-partial-fill. Then, leaving the plunger rod retracted-and-locked overnight so grease settles away from the follower. After that, a worn plunger seal allowing air bypass. Fix: retract and lock the plunger rod, crack the head a quarter turn, pump 8-10 strokes to purge, retighten. If air lock repeats, deep-clean the gun and replace the plunger seal . The longer S-724 barrel cycles the seal more strokes per reload than 500 cc guns, so seal wear accumulates 20-30 percent faster.

How do I fix an S-724 that won't build pressure?

Loss of pressure build has four root causes ranked by frequency. Air lock in the 750 cc reservoir. Next, stuck or contaminated non-return valve in the head. Then, worn plunger seal on the follower rod. After that, blocked coupler or flex hose. Troubleshoot in sequence: prime per the priming FAQ to rule out air lock. Disconnect the coupler and pump the gun into open air to verify grease flow at the head (rules out coupler/hose). If no flow at head, unscrew the head and inspect the non-return valve seat for debris. If valve is clean, check the plunger seal for wear scoring. Parts replacement: valve springs, follower springs and plunger seals are standard spares and ship in the STAR spare-parts kit.

Can I mix different types of grease in the S-724?

No. Never mix grease chemistries in the same gun . Incompatible thickeners separate and can damage bearings. Lithium complex, calcium sulphonate, aluminium complex and polyurea thickeners all use different chemistry and physically separate when combined, forming slurry that blocks bearing seals. To change grease types in the S-724: empty the reservoir completely, unscrew the head, wipe the 750 cc barrel interior with solvent-dampened lint-free rag (reach the full barrel depth), solvent-clean the head internals and non-return valve, reassemble with the new grease. Best practice for fleet operations running multiple grease types: dedicate one S-724 per grease chemistry and label each gun with chemistry and NLGI grade.

How often should I clean the S-724 heavy duty grease gun?

For high-volume fleet-service use (8-10 reloads per shift, 40+ fittings per day), clean the S-724 every 60 days. For regular workshop use (2-5 reloads per shift), clean every 6 months. For occasional service (few reloads per week), annual cleaning suffices. Deep-clean procedure: depressurize the gun by retracting the plunger rod and pressing the bleeder valve, empty the reservoir, unscrew the head and bottom cap, wipe the extended barrel interior with solvent-dampened rag (reach the full barrel length . Longer barrels retain debris in the bottom third), solvent-clean the Quadra-Cut head internals and non-return valve, inspect the plunger rod seal for circumferential wear, reassemble with fresh grease on seals. Replace the plunger seal every 12-18 months of daily use from the STAR spare-parts kit.

Should I store the S-724 horizontally or vertically?

Store horizontally for any period over a week with grease still loaded. Oil bleed (base oil separating from grease thickener) happens faster in partially-loaded high-capacity reservoirs because the extra empty space above the grease column allows movement during handling. Horizontal storage minimizes gravity-driven oil settling in the 750 cc reservoir. Disengage the plunger rod from the side-slot lock so the follower spring keeps the grease column compressed against the head. For storage over 30 days: drain the reservoir completely, wipe the barrel interior with solvent, reassemble with plunger seal lightly greased, store dry at 10-30°C. Never leave the S-724 in open utility-vehicle beds overnight where temperature cycling accelerates oil separation.

What PPE should I wear when using the S-724 at 12,000 PSI?

Mandatory PPE at 12,000 PSI (830 bar): wraparound safety glasses, nitrile chemical-resistant gloves, closed-toe steel-capped boots and long-sleeve protective clothing. Safety rules: never point the coupler or flex hose at any body part, keep the lever-hand behind the coupler head, inspect the 12" flex hose before each use for cracks, bulges or stiffness, never test grease flow by pressing the coupler against skin or fabric. At 12,000 PSI . The maximum working pressure in the STAR range. A pinhole in the hose or an unseated coupler can drive grease through skin and requires immediate surgical treatment. Grease injection injuries can lead to amputation if treatment is delayed. Any suspected injection injury is a surgical emergency, not a minor wound.

What capacity grease gun do I need ; 500 cc, 750 cc or 1000 cc?

Pick by fittings-per-fill target on your typical service job. 500 cc (S-707): 25 fittings per fill, sized for single-bay workshops and occasional service. 750 cc (S-724): 35-40 fittings per fill, sized for fleet-service routes covering multiple machines per shift. 1000 cc (S-732): 50+ fittings per fill, sized for large equipment like mining haul trucks and long conveyors. Trade-off: each capacity step adds gun weight (2.1 kg → 2.5 kg → 2.9 kg loaded) that matters for extended overhead use. Mixed shops often stock the S-707 as primary tool and add the S-724 for multi-machine route days.

Is variable stroke actually useful or just marketing?

Variable stroke is genuinely useful in tight-clearance access situations but irrelevant in open service. The S-724 is a fixed-stroke gun because most high-capacity fleet service has adequate lever-swing clearance. Variable stroke develops full head pressure on partial lever swings, enabling work on fittings where a full lever swing is physically blocked (narrow chassis channels, recessed access panels, tight implement linkages). On the S-724, full lever swings are required to build 12,000 PSI. For tight-clearance work pick the variable-stroke S-724DC instead. For normal fleet-service where handle clearance is not a constraint, fixed-stroke operation is simpler and more positive-feeling. Most operators prefer it once the full-swing rhythm becomes habitual.