Low side, 3-position, hot oil shuttle valve with delayed shift

Capacity: 40 gpm160 L/min. | Cavity: T-33A
DSFD : Low side, 3-position, hot oil shuttle valve with delayed shift
Technical Features [ + ]

Low-side (hot oil) shuttle cartridges allow hot oil to be diverted from the low pressure side of a closed loop system. When both work ports (ports 2 and 4) are at equal pressures the valve is spring-centered to an all-ports-blocked position. When one of the work ports (port 2 or 4) sees a higher pressure the opposite work port is connected to the common port (port 3). The delay shift shuttle prevents flow transients downstream of the hot oil circuit.

  • The valve is designed to center quickly and stay centered until conditions are correct for it to open as explained in the next 2 technical features.
  • The valve prevents flow transients downstream of the hot oil relief in 2 ways. The shuttle stays centered until one side of the transmission actually becomes the low side. Once a low side has been established the valve opens in a controlled fashion after a delay of about 2 seconds.
  • The valve centers and remains centered as long as pressures at ports 2 and 4 are both at or above a value equal to 300 psi (20 bar) plus the setting of the hot oil relief. For instance, if the hot oil relief is set at 200 psi (14 bar) the shuttle will not open unless one side of the transmission drops below 500 psi (34 bar).
  • The spool incorporates a hydraulic stop that eliminates mechanical impact and therefore the potential for internal damage.
  • The hydraulic stop results in a small pilot flow from the high side work port (port 2 or 4) to the common port (port 3).
  • A unique feature due to the hydraulic stop is that the hot oil relief setting can be confirmed with the transmission in neutral.
  • Although this valve goes into a 4-port cavity, the nose (port 1) is not used.
  • Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations.
Technical Data [ + ]
Note: Data may vary by configuration. See CONFIGURATION section.
Cavity T-33A
Series 3
Capacity 40 gpm160 L/min.
Maximum Operating Pressure 5000 psi350 bar
Pilot Flow 23 in³/min.0,38 L/min.
Valve Hex Size 1 1/4 in.31,8 mm
Valve Installation Torque 150 - 160 lbf ft203 - 217 Nm
Model Weight 1.40 lb0,65 kg
Seal kit - Cartridge Buna: 990033007
Seal kit - Cartridge Polyurethane: 990033002
Seal kit - Cartridge Viton: 990033006
Performance Curves [ + ]
FAQs [ + ]

Direct-acting valves are used to prevent over pressure, and pilot-operated valves are used to regulate pressure. If you are unsure, use a direct-acting valve. Sun's direct acting valves are very fast, dirt tolerant, stable, and robust. Sun's pilot-operated valves are moderately fast, they have a low pressure rise vs. flow curve, and they are easy to adjust.

There are exactly 250 Sun drops in a cubic inch or 15 in a cc.

Only external seals are serviceable.  Sun offers replacement seal kits for all cartridge models. The applicable kit part number can be found in the product page's Technical Data table or by using our Cartridge Seal Kit search function located under Accessories. Please note: Converting the external seals from one material to another does not ensure fluid compatibility with that material due to the existence of internal seals within the cartridge.
Additional Resources [ + ]