Cat Pump 66DX35G1I Plunger Pump 1" 3400 RPM Direct Drive Triplex Pump
The Cat Pump 66DX35G1I is a direct drive triplex plunger pump built for equipment that needs steady high pressure without a belt drive or gearbox in the way. It flows up to 3.5 GPM and handles pressures up to 4000 PSI while turning at 3400 RPM, and the 1" hollow straight shaft bolts the pump straight onto a gas engine flange. That layout keeps the whole assembly short, light and simple to service, which is why the 66DX series shows up so often on skid-mounted washers, cart units and portable cleaning rigs where space is tight and downtime is expensive.
Inside, the pump follows the same construction philosophy Cat Pumps has used for decades. Three solid ceramic plungers ride against long-life NBR seals, the valve assemblies are 304 stainless steel, and the manifold is brass. Spring-loaded closed and hydraulically opened inlet and discharge valves keep flow smooth and pulsation low, so nozzles, guns and downstream fittings see far less hammering than they would with a lesser pump. The result is a pump that holds its pressure rating hour after hour instead of fading partway through a shift.
Because it is a positive displacement design, the 66DX35G1I moves the same volume every revolution regardless of what the discharge line is doing, which makes it predictable to size and easy to pair with an unloader. It suits pressure washing, general surface and equipment cleaning, agricultural spraying, misting and cooling, car and truck wash bays, industrial parts and floor cleaning, and a wide range of contractor and municipal work. Paired with a suitable engine in the 13 HP range, it gives a compact, rebuildable core that can be resealed in the field rather than replaced outright.
Key Features
- Triplex three-plunger positive displacement design for smooth, low-pulsation flow
- Direct drive with 1" straight hollow horizontal shaft that mounts to a gas engine flange
- Solid ceramic plungers for long wear life against abrasive and hard water
- Brass manifold with 304 stainless steel valve assemblies
- Spring-loaded closed, hydraulically opened inlet and discharge valves
- Standard NBR (Buna-N) seals and O-rings
- Supplied with mounting flange, unloader and fixed chemical injector
- Fully rebuildable with readily available Cat Pumps service kits
- Compact footprint that eliminates belts, pulleys and guards
Applications
- Portable and skid-mounted pressure washers
- Vehicle, truck and fleet washing
- Equipment, engine and parts cleaning
- Concrete, deck and building surface cleaning
- Agricultural and horticultural spraying
- Misting, humidification and evaporative cooling
- Industrial floor and plant sanitation
- Contractor, rental and municipal maintenance rigs
Specifications
- Model: 66DX35G1I
- Pump Type: Triplex plunger, positive displacement
- Drive: Direct drive, flange mount
- Maximum Flow: 3.5 GPM (13.2 LPM)
- Maximum Pressure: 4000 PSI
- Pressure Range: 100–4000 PSI
- Maximum RPM: 3400
- Shaft: 1" straight hollow horizontal shaft
- Inlet Port Size: 1/2" NPT female
- Discharge Port Size: 3/8" NPT male
- Bore: 14 mm
- Stroke: 10 mm
- Manifold Material: Brass
- Valve Assemblies: 304 stainless steel
- Plungers: Solid ceramic
- Seals and O-Rings: NBR (Buna-N)
- Crankcase Oil Capacity: 18 oz (oil not included)
- Maximum Liquid Temperature: 140°F
- Recommended Engine Size: approximately 13 HP gas
- Dimensions: 11.73" x 10.51" x 8.15"
Frequently Asked Questions
Q: Does the 66DX35G1I arrive filled with crankcase oil?
A: No. The crankcase ships dry and must be filled with 18 oz of the correct pump oil before the first start. Running it dry even briefly will damage the crankcase bearings.
Q: Can this pump be belt driven instead of engine mounted?
A: No. The 66DX35G1I uses a 1" hollow shaft designed to slide onto an engine shaft and bolt to the flange. A belt drive setup requires a different pump configuration with a solid shaft.
Q: What water supply does the pump need at the inlet?
A: It needs a flooded, unrestricted supply that comfortably exceeds 3.5 GPM through the 1/2" inlet. Starving the inlet is the fastest way to cavitate the pump and shorten seal life.
Q: Can it run warm or heated water?
A: Standard NBR seals handle liquid up to 140°F. Anything hotter calls for a high temperature seal configuration, since heat is the most common cause of premature packing failure.
Q: Is the pump rebuildable rather than replaceable?
A: Yes. Seals, valves and plungers are all serviceable items, and complete seal and valve kits are available so a worn pump can be brought back to full pressure in the field.
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