SUN HYDRAULICS
PK2

$669.20 USD

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SUN HYDRAULICS
Material:PK2
Summary:Manifold

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***Disclaimer: The following summary contains information gathered from various sources such as product descriptions, technical specifications and catalogs. While efforts have been made to provide accurate details, inaccuracies may occur. It is advised to verify all information by contacting Sun Hydraulics directly.***
The Sun Hydraulics PK2 (Material Number: PK2) is a sandwich body hydraulic manifold designed to function as a reducer/reliever on port A with a reverse flow check and external port 4, compatible with ISO 07 interface standards. This model features a stack height of 3.52 inches (90 mm) and is equipped with SAE 6 port sizes. The manifold incorporates open cavities labeled T-23A, which facilitate its integration into larger hydraulic systems. Constructed from 6061-T651 aluminum, this manifold offers excellent corrosion resistance while maintaining a balance of strength and machinability. The design includes Sun's distinctive profiling on the ends, providing aesthetic appeal and functional alignment when stacking multiple units. This product is particularly suited for applications requiring pressure reduction and relief functions in hydraulic circuits, ensuring smooth operation under varying flow conditions. With an emphasis on maintaining dry o-ring sealing surfaces during assembly, the PK2 helps prevent potential fluid leaks in pressurized environments.

Description

Body Type	SandwichSandwich
Interface	ISO 07ISO 07
Body Features	Reducer/reliever on A with reverse flow check and port 4 externalReducer/reliever on A with reverse flow check and port 4 external
Stack Height	3.52 in.90 mm
Open Cavities	11
Cavity	T-23A
Port Size	SAE 6SAE 6

Show FAQ

Why does Sun profile the ends of your sandwich manifolds? Is there a functional reason?	In the beginning, the bosses (profiles) were cylindrical and centered on the cavity. The boss created a consistant locating spot for the fixture that put in the bolt through holes. The first step in machining sandwiches was to put in the cavities and this was done using big old #4 Warner-Swazey turret lathes. Adding the circular boss was practically free at this point. When 2 or more sandwiches are stacked they look designed rather than a random stack of blocks. This was deemed esthetically pleasing and became a Sun trademark. You can spot Sun sandwiches from across a factory floor. We switched to CNC in the early 80's but kept the circular boss. At this time the first sandwich with 2 cavities on one side was designed, the YFCG XHN AA. Obviously we could not use a circular boss centered on a cavity; we tried a partial circular boss centered on both of the cavities, but the resulting appearance was poor. The solution was a rectangular boss with radiused corners. The resulting profile was pleasing and more modern looking than the circular boss and served a functional purpose--less material had to be removed. We changed all the other sandwich bosses to match. We have applied the boss profile to some custom manifolds.....just because it looks good.
How can I assemble a stack of sandwiches and keep it dry?	Make sure the surfaces are flat and that there are no burrs. Do not polish the surface; machining marks are good. The machining marks help stop the o-rings from acting as pumps. Look for dings on the corners of seal plates that will create gaps. Stud rods or cap screws must not bottom out in the sub-plate. It is very important to assemble a stack of sandwich valves keeping the o-ring sealing surfaces “dry.” The hydrostatic properties of an oil film under the o-rings, and at the seal plate interface, can create a fluid path leading from the pressurized port interfaces to the outside edge of the stack. (Under this condition, as noted in bullet point above, an o-ring can actually act as a “pump.”) So, if you start with a wet seal interface in your stack, there’s a good chance it will always stay wet.
Why does Sun use 6061 aluminum?	6061-T651 is relatively strong, relatively inexpensive, difficult to machine, readily available in all shapes and sizes and very corrosion resistant. 2024 is stronger and machines beautifully, but is expensive and falls to pieces in a corrosive environment.
Why doesn't Sun anodize their aluminum bodies?	Reasons to anodize: To increase corrosion resistance. Sun uses 6061-T651 aluminum. It is one of the most corrosion resistant aluminum alloys there is. Whether or not anodizing improves the corrosion resistance of 6061 aluminum is debatable. We have yet to have a manifold returned because of corrosion. Appearance (color). The 2 colors that would appeal to Sun would be blue or black. Unfortunately these are the colors that are hardest to do consistently. To provide a hard wear surface. Sun does not make parts-in-body valves. The manifold is just plumbing. We don't need a wear surface. Because everyone else does it. Bad reason. Reasons to not anodize: Cost. It's another process. Logistics. When you make tens of thousands of manifolds a month and you anodize hundreds, it's a problem. Consistency. See above. Stamping. After a body is anodized you cannot do any more stamping without making a mess.Inspection. Have you ever tried to look for burrs in a black anodized body? It's the old blackboard factory at night scenario. Torque. You will experience an increase in breakaway torque when removing items from an anodized manifold. Fatigue life. This is the best reason to not anodize. Fatigue failure is a very complex phenomenon. What it takes to initiate a crack is difficult to predict. What it takes to propagate a crack is readily defined. Anodizing produces a very thin, very hard, and very brittle surface on aluminum. The first time you pressurize an anodized aluminum manifold you have initiated fatigue cracks. Whether or not the stress is enough to propagate the cracks is a matter of pressure and manifold geometry. Anodizing an aluminum manifold grossly reduces the fatigue life by anywhere from 20% to 50%.
I need a reducer on B. Can I connect the drain to A?	Yes. If you look in the sandwich section you will see that we offer many such packages. When you are pressurizing B, A is connected to tank, allowing the reducer to do its job. When you reverse, the drain or tank port of the reducer is pressurized by A. This increases the setting of the reducer and helps keep the reducer open in the reverse flow direction.
How big is a drop of hydraulic oil?	There are exactly 250 Sun drops in a cubic inch or 15 in a cc.

Additional Resources

Notes:

Stack height value in technical data table includes seal retainer plate.
Important: Carefully consider the maximum system pressure. The pressure rating of the manifold is dependent on the manifold material, with the port type/size a secondary consideration. Manifolds constructed of aluminum are not rated for pressures higher than 3000 psi (210 bar), regardless of the port type/size specified.

SUN HYDRAULICSPK2

Additional Resources

SUN HYDRAULICS
PK2