Graco 15H840 Displacement Rod
The 15H840 is a genuine Graco **displacement (piston) rod**. It plays a critical role in the pump mechanism by transferring drive motion into the fluid section, enabling efficient fluid displacement during both up-stroke and down-stroke. Over time, wear to this rod can cause **pressure loss**, **leakage**, or erratic spray behavior — replacing it can restore smooth and consistent performance.
Key Features & Highlights
- OEM Graco part, part-number 15H840 :contentReference[oaicite:0]{index=0}
- Precision-machined chrome-plated steel for durability and minimal friction
- Designed for use in Graco displacement (reciprocating) pumps
- Helps maintain consistent fluid flow and spray pressure when in good condition
- Replace when visible scoring, plating wear, or performance drop is observed
Specifications
| OEM Part Number |
15H840 |
| Type |
Displacement / Piston Rod |
| Material |
Chrome-plated steel |
| Typical Use |
Reciprocating pump drive |
Compatible Machines
Publicly available documentation on machines that use **15H840** is very limited. However, in the Graco parts list for certain **Viscount I** reciprocators, **15H840** is listed as the rod for the **253608** version. :contentReference[oaicite:1]{index=1}
- Graco **Viscount I Reciprocator**, Series A (253608) :contentReference[oaicite:2]{index=2}
*Note: Always cross-check your sprayer’s parts diagram or service manual to confirm compatibility before ordering.*
Installation & Maintenance Tips
- When removing the old rod, relieve all pressure following the sprayer’s pressure-relief procedure. :contentReference[oaicite:3]{index=3}
- Use a proper **spanner wrench** on the flats or pin-holes (if the rod has them) to unscrew the piston safely. :contentReference[oaicite:4]{index=4}
- Apply **thread lubricant** on the threads during reassembly to prevent galling and ensure correct torque. :contentReference[oaicite:5]{index=5}
- Inspect related pump components (packings, wipers, bearings) and replace if worn — a new rod may accelerate wear on old seals.
- After installation, run the pump at low pressure first to check for leaks or abnormal noises, then gradually ramp up to working pressure.
Benefits of Replacement
- Restores **consistent hydraulic or fluid pressure**, reducing spray defects.
- Extends life of **packings and piston components** by ensuring a smooth, even stroke.
- Reduces maintenance downtime compared to letting a worn rod damage other internal parts.
Frequently Asked Questions
Wear is usually caused by friction against the packing and seals. Over time, scoring or corrosion can occur, especially if the pump is run with worn packings or contaminated fluid.
Look for visible wear like grooves, discoloration, or uneven plating. Also monitor performance: if you notice pressure drop, erratic spray, or fluid leakage, replacing the rod is a good first step in servicing.
It may be possible if they’re in good condition, but it’s often safer and more reliable to replace the trip-rod, piston, and seals along with the displacement rod. This ensures full performance and avoids premature failure.
You can find the OEM 15H840 rod from authorized Graco parts distributors and industrial parts suppliers. :contentReference[oaicite:6]{index=6} Make sure to verify that it's a genuine part.
