FEATURES

• Separate Vatve Plate—Separate hardened alloy steel valve plate resists wear. Unidirectional designs include a precompression orifice from the discharge port to the approaching cylinder. This method allows a uniform, gradual pressure rise from inlet to outlet to minimize mechanical shock and the resultant noise. A decompression orifice communicates with the cylinder approaching the inlet port to the pump case. This decompresses the oil that remains in the cylinder after leaving the discharge port. This increases volumetric efficiency and promotes stlffer systems by providing a means to remove air-entrained oil from the circuit.
  
  
• Forged Rotor—One-piece forged bronze rotor resists wear, pick-up, and fretting caused by fluid-borne contaminants or low-lubricity fluid conditions. Rotor is spllned to permit axial motion to compensate for fluid film thickness and temperature changes.
  
  
• Ball-Shoe Pistons—The ball of the piston knuckle joint is formed on the piston shoe. This reduces the overall piston length and the resultant side force on the cylinder bores.
  
  
• Roller Bearings—Dual, heavy duty, tapered roller bearings support the drive end of the input shaft. They are lubricated by the hydraulic fluid and designed to accept external side loads normally encountered in belt-drive applications.
  
  
• Reaction Plate Assembly—Heavy forged steel reaction plate assembly has a separate hardened alloy steel thrust plate, to distribute wear and reduce repair costs.
  
  
• Dual Holddown System—Individual piston springs preload the entire piston assembly against the thrust plate. A fixed-clearance mechanical retainer assembly holds the piston shoes against the thrust plate. Compared to single-spring holddown systems, which retain only the piston shoe, this method reduces mechanical lash, wear of the piston knuckle, and related noise generation,
  
  
• Opposed Control Pistons—Displacement changes are rapid and stable due to the high positioning force available from the line pressure operated controls. The opposed pistons hydrau-lically "clamp" the displacement changing mechanism for optimal delivery stability.
  
  

BENEFITS

• Lower System Costs—The high-pressure capability of these units permit the use of smaller size system components to handle the same horsepower at lower cost. Heavy-duty shaft bearings accept overhung loads, eliminating the need for a countershaft on most indirect drives.
  
  
• Lower Operating Costs—High overall efficiencies and power-saving controls reduce power consumption and cooling requirements.
  
  
• Extended Service Life—Tough alloy bronze mated to hardened alloy steels in the rotating group, and heavy-duty bearings are used throughout the pump to provide long life operation.
  
  
• Repairable—Designed to permit easy field service. All parts subject to wear are field serviceable.
  
  
• Low Noise Levels—Preloaded pistons, unique port timing, and rigid case construction yield low noise levels (PV320 83.5 dBa at 1800 RPM, 4000 psi, 24 GPM).