S-711DP Lever Action Grease Gun

Frequently Asked Questions: S-711DP Dual Piston Lever Action Grease Gun

What is a dual piston lever grease gun?

A dual piston lever grease gun uses two parallel pump pistons instead of one to deliver more grease per lever stroke at the same peak pressure. On the S-711DP, each full lever stroke moves 2.4 grams of grease through the non-return valve into the coupler, approximately three times the 1 gram per stroke output of a standard single-piston lever gun. The architecture is purpose-built for operators servicing large fitting counts where total pumping time is a real productivity constraint, and for cold-weather service where the supporting dual-inlet feature prevents loss of prime on reload.

How many grams of grease does a dual piston lever grease gun deliver per stroke?

The S-711DP delivers 2.4 grams of grease per full lever stroke, or 1 oz. per 12 strokes. By comparison, standard single-piston lever guns deliver 1 gram per stroke or 1 oz. per 28 strokes. Across a 30-fitting service round at roughly 12 grams per fitting, the S-711DP pumps approximately 150 strokes versus 360 on a single-piston gun. The time difference is usually 5 to 10 minutes per heavy machine, which across a fleet-depot shift covering 5-10 machines compounds to 30-90 recovered minutes per operator.

How does a dual piston grease gun deliver 2-3x output per stroke?

Two pump pistons operate in parallel on every stroke of the lever handle, displacing roughly three times the grease volume of a single-piston pump on the same stroke. Each piston has its own bore and its own non-return valve arrangement inside the head. When the lever is pumped, both pistons move simultaneously, and both discharges combine into a single outlet flow through the coupler. Peak pressure stays at 12,000 PSI because pressure is set by the piston-area-to-lever-arm ratio, not by piston count; what doubles is the volume moved per stroke, which is what "2.4×" and "three times" refer to.

How does a dual piston grease gun prevent loss of prime in cold weather?

The dual grease inlet in the head feeds both pistons through two separate channels, so if one channel draws air during reload or cold-start, the other channel still feeds grease and the pump primes on the first stroke. Single-inlet guns lose prime when cold grease thickens and pulls away from the feed channel opening, or when the follower plate stops in a position that leaves air above the grease column. On the S-711DP, one inlet drawing air doesn't stop the pump because the second inlet is still supplying grease. Operators in northern European, Scandinavian, Canadian, and Himalayan service report the dual inlet as the single feature that most reliably eliminates the priming problem on cold mornings.

How does variable stroke work on a dual piston grease gun?

The lever-and-pump geometry is designed so that a partial swing of the handle, around 30 to 40 percent of the full arc, still builds the full 12,000 PSI pressure at the coupler. On a fixed-stroke gun, a partial lever swing builds proportionally lower pressure (so a 50 percent swing builds 6,000 PSI, not 12,000). Variable stroke overcomes that by using a mechanism that develops full pressure over whatever arc is available. The feature matters on fittings where a full lever swing is physically blocked by surrounding machine structure: excavator pin clusters behind hydraulic lines, implement linkages behind chassis members, overhead service points with low ceiling clearance.

What is the difference between 6000 PSI and 12000 PSI dual piston grease guns?

12,000 PSI is the top pressure tier for hand-operated grease guns and the pressure level that clears crusted zerk fittings on equipment that has sat outdoors between service intervals. At 6,000 PSI, fittings with dried or contaminated grease often refuse fresh grease, and the operator either skips the fitting or double-pumps it (which can blow adjacent seals). At 12,000 PSI, the gun reliably punches through the crust on the first or second stroke. For light-duty workshop service where fittings are clean and well-maintained, 6,000 PSI is adequate and the pressure margin is not needed. The S-711DP at 12,000 PSI is over-specified for bench workshop use and correctly specified for fleet, agricultural contractor, construction, and mining service where outdoor exposure between services is routine.

How do you prime a dual piston grease gun for first use?

Load the reservoir, release the plunger rod from the side slot, crack the head a quarter turn, and pump the lever 3 to 5 full strokes with the coupler disconnected. Grease should flow from the head seam by the second or third stroke because both inlet channels are drawing simultaneously. Retighten the head when grease flows without air bubbles. If priming takes more than 5 strokes on a warm reload, the follower plate may not be compressing the grease column (check the plunger rod is released), or the reservoir may be incompletely packed with air voids (redo the bulk fill, pressing grease firmly against the sidewalls). In cold weather, expect slightly more strokes because grease viscosity increases.

Can a dual piston grease gun reach tight spaces that single piston cannot?

Yes, because the variable stroke mechanism lets the operator build full 12,000 PSI pressure on partial lever swings, reaching fittings where a full lever swing is physically blocked. On a fixed-stroke single-piston gun, a tight-clearance fitting forces the operator to either move the machine structure (often impractical) or accept lower pressure from a partial swing (often inadequate for a crusted zerk). On the S-711DP, a 30 percent lever arc still produces 12,000 PSI at the coupler, so the operator can service excavator pin clusters, implement linkages, overhead service points, and other access-constrained fittings that would otherwise be skipped or double-serviced with a pistol grip gun.

Can I use a dual piston lever grease gun on a tractor?

Yes. Agricultural tractor service is one of the primary use cases for the S-711DP. A modern tractor has 25 to 40 grease points across chassis, steering linkages, PTO shafts, 3-point hitch pivots, implement couplers, and wheel bearing fittings. The S-711DP's 500 cc reservoir at 12 grams per fitting covers 40 fittings per fill (most tractors in one fill). The dual-piston output cuts total pumping time by roughly a third versus a standard gun, saving real minutes on multi-tractor contractor routes. The dual grease inlet is particularly valuable on tractors that sit in paddocks or fields between services, where single-inlet guns often need re-priming after overnight exposure.

Is a dual piston grease gun better for 1000+ grease fittings?

For routes where a single operator greases many fittings per shift, yes. A dual-piston gun covers the same route in about a third of the pumping time, which on 1,000 fittings is the difference between one shift and almost two. At 12 grams per fitting and 1 gram per stroke on a standard gun, 1,000 fittings take 12,000 strokes. On the S-711DP at 2.4 grams per stroke, the same 1,000 fittings take 5,000 strokes. The operator still needs to move between fittings, connect and disconnect the coupler, and handle reloads, so the total time saving is less than the stroke-count saving, but it is typically 25-35 percent. For high-volume routes this is the difference between covering the route on schedule and falling behind.

How do I fix air lock in a dual piston grease gun?

Crack the head a quarter turn to open the air release path, then pump the lever 3 to 5 strokes with the coupler disconnected. Retighten the head when grease flows from the seam without bubbles. Air lock on the S-711DP is less common than on single-inlet guns because the dual inlet feeds both pistons through separate channels, so one channel drawing air rarely stops the pump. If priming still fails after 5 strokes: check that the plunger rod is released from the side-slot lock (the follower spring needs to compress the grease column against the head); inspect the bulk fill for air voids at the sidewalls (redo the fill if needed); and in cold weather, give the grease time to warm to operating temperature before priming.

Can I mix different grease types in a dual piston grease gun?

No. Mixing grease chemistries (lithium, calcium, aluminium complex, polyurea, clay) can cause chemical reactions that form hard deposits and clog the pump, the dual inlet channels, and the non-return valve. Symptoms of incompatible mixing: grease goes lumpy or crumbly, pumping becomes erratic, the gun loses prime frequently, and the grease loses water resistance and heat stability. Workshops running multiple grease types should keep dedicated labelled guns per grease chemistry. To safely switch grease types in the S-711DP: empty the reservoir, unscrew the head and barrel, wipe out old grease with a lint-free rag, solvent-flush the head and barrel with mineral spirits, dry completely, lightly re-grease the plunger rod seal with a compatible grease, and reload with the new grease.

How often should you clean a dual piston grease gun?

Every 3 months for continuous professional use, every 6 months for regular workshop use, or annually for occasional service. Deep-clean procedure: depressurise the gun by retracting the plunger rod and pressing the bleeder valve, empty the reservoir, unscrew the head and barrel, wipe the barrel interior with solvent-dampened lint-free rag, solvent-clean the dual inlet channels and non-return valve (a small brush helps reach the inlet paths), inspect the follower plate seal and plunger rod seal for circumferential wear, reassemble with fresh grease lightly applied to seals. Replace worn seals from the STAR spare parts kit. The dual-inlet architecture accumulates slightly more debris than single-inlet guns because there are two flow paths to keep clean; scheduled cleaning prevents the build-up from affecting priming reliability.

Should I store a dual piston grease gun horizontally or vertically?

Horizontally, with the plunger rod disengaged from the side-slot lock. Oil bleed (base oil separating from grease thickener) happens faster in vertical storage because gravity pulls oil toward the bottom of the reservoir. Horizontal storage minimises the bleed. Releasing the plunger rod lets the follower spring keep the grease column compressed against the pump chamber, which reduces air exposure inside the reservoir. For storage over 30 days: drain the reservoir completely, solvent-clean, and store dry with the plunger seal lightly greased. Never leave the gun in open utility-vehicle beds or outdoor tool-boxes overnight where temperature cycling accelerates oil separation.

What PPE should you wear when using a 12,000 PSI dual piston grease gun?

Mandatory PPE at 12,000 PSI (830 bar): wraparound safety glasses, nitrile chemical-resistant gloves, closed-toe steel-capped boots, 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 a pinhole in the hose or an unseated coupler can drive grease through intact skin. Grease injection injuries require immediate surgical treatment regardless of initial wound appearance; untreated injection injuries can progress to tissue necrosis and amputation. Any suspected injection injury is a surgical emergency, not a minor wound.

What is the difference between a dual piston and single piston lever grease gun?

A dual piston gun moves roughly three times the grease per stroke, has the dual-inlet prime reliability feature, and typically supports variable stroke; a single piston gun is lighter, mechanically simpler, and typically sits at an entry price point. For high-volume service (fleet routes, agricultural contractor work, large equipment maintenance), the dual-piston output recovers enough pumping time to justify the weight and mechanical-complexity premium. For single-bay workshop service, occasional grease jobs, or service work where overgreasing would damage small bearings, a standard single-piston gun like the S-707 is correctly sized and simpler to maintain. The decision comes down to fitting count per shift: below 50 fittings per shift, single-piston is right; above 200 fittings per shift, dual-piston pays back quickly.