S-706B Lever Action Grease Gun

Frequently Asked Questions: Medium Duty Lever Action Grease Gun 6,000 PSI

What is the best medium duty lever grease gun for daily use?

A 6,000 PSI medium duty lever action grease gun like the S-706B is the workhorse tool for professional automotive, agricultural, and general workshop lubrication service. At 6,000 PSI (413 bar) it clears most chassis zerks, tractor U-joints, suspension bushings, wheel bearing fittings, forklift pivots, and general equipment lube points. The 14 oz. (400 g) cartridge or 500 cc bulk capacity covers a full workshop shift without reloading. The S-706B sits between standard 3,000 PSI service guns and heavy 10,000+ PSI industrial tools, matching the pressure profile of 85 percent of working zerk fittings in automotive chassis, agricultural tractor, and fleet maintenance applications.

What PSI does a medium duty lever grease gun produce?

The S-706B develops 6,000 PSI (413 bar), the reference working pressure for medium-duty lever grease guns. It clears about 85 percent of the zerk fittings found in automotive, agricultural, and light industrial service. Typical applications handled comfortably at this pressure include car and light truck chassis joints, tractor 3-point hitches, PTO U-joints, trailer spindles, Bearing Buddies, forklift mast pivots, and garage door tracks. Fittings that actually need 10,000-12,000 PSI are the exception: badly crusted zerks on neglected equipment, 20+ ton excavator pins, and heavy construction machinery with hardened grease deposits. For those, the S-707 at 12,000 PSI is the right step up.

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

The S-706B delivers 1 gram of grease per stroke, which works out to 1 oz. per 28 strokes or a full 14 oz. / 400 g cartridge in approximately 400 strokes. This output is controlled by the 57.15 mm barrel diameter and piston stroke length, and matches the delivery rate of other medium duty lever guns in the STAR range. Technicians can count strokes to meter grease accurately: typical chassis zerk takes 3-5 strokes (3-5 g), U-joint 5-8 strokes, wheel bearing 10-15 strokes, heavy equipment pin 15-25 strokes. Log stroke counts during service routes to calibrate grease consumption per fitting.

What is 4-way loading on a grease gun?

4-way loading means the S-706B accepts four different fill methods: cartridges, bulk pack, suction fill, and filler pump. The standard worldwide 14 oz. cartridge remains fastest for single-fill shop service. Bulk pack from an open pail is the economy route for high-volume operations. Suction fill and filler-pump connection through the head's 1/8 BSPT inlet add flexibility for shared workshop bays. Commodity 2-way and 3-way guns skip one or both alternatives; 4-way is what separates medium-duty lever guns from standard-tier lever guns.

How do you prime a medium duty lever grease gun?

Prime the S-706B after every reload with a brief three-stage sequence: release air at the head, pump the lever to fill the chamber, then test at a fitting. Start by loosening the head cap a quarter turn to open the bleed path. Pump the lever slowly 3 to 5 times until grease flows from the head with no air bubbles, then retighten. Give the lever another 2 or 3 firm pumps to bring the system to working pressure. Finally, connect the coupler to a zerk and confirm fresh grease flows by the second stroke. If nothing flows after these steps, the cartridge may have emptied, air may have worked past the plunger, or the follower plate may have tilted and lost contact with the grease column.

Can I use a lever grease gun for a tractor?

Yes. Agricultural tractor service is one of the primary applications for the S-706B. Typical tractor greasing schedule every 50-100 operating hours: front steering kingpins (3-5 strokes each), tie rod ends (3-5 strokes), U-joints on drive shaft (5-8 strokes), PTO shaft slip yokes (5-8 strokes), 3-point hitch pivots (2-4 strokes), loader arm pivots (5-10 strokes), front axle pivots (5-10 strokes), cab door hinges (1-2 strokes). A 100 HP tractor has 15-25 grease fittings per service. Use NLGI 2 moly EP for drive shafts and U-joints, NLGI 2 lithium for general chassis, water-resistant calcium sulfonate for implements that contact mud.

Can I use a lever grease gun for Bearing Buddies?

Yes, bearing Buddy style spring-loaded spindle caps are designed specifically for grease gun filling. The S-706B works directly with them. Procedure: engage the coupler with the grease fitting on the Bearing Buddy, pump one lever stroke at a time while watching the spring-loaded piston on the front of the cap. Stop pumping the moment the piston moves forward 1-2 mm, which indicates the hub cavity is full. Over-pumping past this point blows the rear seal and contaminates the hub bearings with trapped grease pressure. For seasonal storage, leave Bearing Buddies fully packed. They compress slightly during storage and need topping up each spring before launch. Use marine-grade NLGI 2 calcium sulfonate grease for water resistance.

Can I use a lever grease gun for an excavator?

The S-706B works well on smaller excavators (5-10 ton class) and compact track loaders with regular greasing schedules, but heavy 20+ ton class machines or severely crusted fittings need 10,000-12,000 PSI. For light-to-mid excavator service with the S-706B: use NLGI 2 moly EP grease formulated for heavy shock loads, inspect each pin for wear before re-greasing, grease with the boom parked on the ground and engine off. Pump 10-20 strokes per pin depending on pin size and mileage since last service. For 20+ ton class excavators, heavy industrial diggers, or mining equipment, step up to the 12,000 PSI S-707.

How to prevent air lock in a lever grease gun?

Air lock is best prevented by careful reloading and attention to seal wear on the S-706B. After every cartridge change or bulk reload, loosen the head cap a quarter turn and pump three strokes until grease flows through the loosened joint, then retighten. Never let a cartridge run completely empty before reloading. Once the follower plate drops below the grease column it pulls air in behind the plunger. During annual service, inspect the plunger rod seal and replace if worn. Store the gun with a fresh cartridge loaded rather than empty, and for long storage back off the lever fully so residual pressure does not pull air through the seals. If air lock still occurs, unscrew the head, press grease down manually with a spoon to eliminate the air gap, reassemble, and re-prime.

Why does my lever grease gun stop pumping after loading?

A primed lever gun that suddenly stops pumping almost always comes down to one of four root causes: an empty cartridge, air past the seals, a tilted follower plate, or a check valve blocked by grease debris. Diagnose by pulling the plunger rod back first. If it resists, grease is still loaded. If it moves freely, the cartridge is empty and needs reloading. Next, re-prime by loosening the head cap and pumping until grease flows. If priming fails, unscrew the head and inspect the check valve for grease debris. When the check valve moves freely but priming still fails, the plunger rod seal has likely worn and needs replacing from a spare parts kit.

Can I mix different greases in one grease gun?

Mixing lithium and calcium greases in the S-706B causes chemical incompatibility. The mixed grease forms hard deposits, loses lubricating properties, and can clog internal check valves and the follower plate. Lithium thickener and calcium sulfonate thickener are incompatible at the soap-base level even when both are NLGI 2 viscosity. Symptoms include grease turning crumbly or lumpy, erratic pumping, rapid prime loss, and loss of water resistance and heat stability. To recover after an accidental mix, empty the gun completely, solvent-flush the barrel and head with mineral spirits, dry thoroughly, lightly regrease the plunger rod seal with a compatible grease, and reload with a single grease type. Workshops servicing mixed fleets should keep one dedicated gun per grease type with each clearly labeled.

How often should I clean a lever action grease gun?

The S-706B has a three-level maintenance cadence: external wipe-down after every use, a deep clean of the barrel and follower plate every 3-6 months under continuous professional use, and annual disassembly to inspect the plunger rod, follower-plate seal, check valve, and head seals. For a deep clean, unscrew the head, remove the cartridge or bulk grease, wipe the barrel interior with a solvent-dampened rag, and inspect the follower plate for wear or cracking. Check the plunger rod seal, solvent-clean the head and check valve, then reassemble with fresh grease lightly applied to the plunger rod seal. Replace worn seals from the STAR spare parts kit. Workshops running 10+ reloads per shift should clean every 90 days. Occasional use of a few reloads per week can go 12 months between deep cleans.

How to store a lever grease gun between uses?

Storage method depends on duration. For daily storage, hang the S-706B vertically head-up with a loaded cartridge and the lever backed off so no residual pressure remains. For storage over 30 days, clean external grease from the coupler and hose, back the lever off completely, keep the cartridge loaded to prevent air ingress through the seals, and store in a dry location between 10-30°C away from direct sunlight (which degrades the hose and seals). Avoid temperature extremes that separate grease oils from the soap base. After a stretch of 30+ days in storage, pump 3-5 strokes to waste before greasing actual fittings to clear any oxidized grease or separated oil at the head. For year-plus storage, drain the gun completely, clean it, and store dry with the plunger rod seal lightly greased.

What PPE is mandatory for medium duty grease gun work?

Operators should wear wraparound safety glasses, nitrile gloves, closed-toe shoes, and long sleeves when working at face height with the S-706B. A few safety rules are non-negotiable at 6,000 PSI (413 bar). Never point the coupler or hose at any part of your body, and keep hands behind the coupler rather than in front. Inspect the 12 inch flexible hose before each use for cracks, bulges, or stiffness that signal an imminent burst, and never test the gun by pressing the coupler against skin or fabric. If grease injection does occur (a small puncture with waxy pale skin around it), treat it as a surgical emergency and go to hospital immediately. A 6,000 PSI injection injury is not a minor puncture. Injected grease does not absorb and requires surgical removal within hours to prevent tissue damage.