MODEL

XRDB

Hydrostatic transmission flushing assembly with cross-port relief

CAPACITY: 40 L/min.

CONFIGURATION

L Control Standard Screw Adjustment

A (with RDDA3 primary cartridge, Non-

adjustable direct-acting relief valve)

W Port and

Material

Designation

Ports 1 & 2 — 3/4" BSPP; Port T —

3/8" BSPP; Gage Ports — 1/4" BSPP;

Mounting Holes — M10 x 1.5-6H x .62

DP; Aluminum

This valve assembly provides high pressure cross-port relief protection and a flushing circuit for hydrostatic

transmissions. The hot oil flushing circuit allows a discharge of oil from the low pressure side of the loop. The

charge pump replaces the hot, dirty oil with cool, filtered oil. The hot oil discharge is often passed through the

cases of the pump and the motor, flushing hot, dirty oil from them as well.

A mechanical brake is recommended to positively lock any stopped live load.

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.

For detailed information regarding the cartridges contained in this assembly, click on the models codes shown in the Included Components tab.

MODEL

XRDB

Hydrostatic transmission flushing assembly with cross-port relief

CAPACITY: 40 L/min.

Standard Setting

B 300 - 1500 psi (20 - 105 bar), 1000 psi (70 bar)

Standard Setting

C 1000 - 6000 psi (70 - 420 bar), 1000 psi (70 bar)

Standard Setting

D 200 - 800 psi (14 - 55 bar), 400 psi (28 bar) Standard

Setting

E 100 - 400 psi (7 - 28 bar), 200 psi (14 bar) Standard

Setting

S 50 - 200 psi (3,5 - 14 bar), 100 psi (7 bar) Standard

A A (with RDDA3 primary cartridge, Non-adjustable direct-acting relief valve)

PORT DESIGNATORS

MATERIAL DESIGNATOR No modifier - inch, aluminum /S - Inch, Ductile Iron /M - Metric, Aluminum /T - Metric, Ductile Iron

A unique feature of the hot oil shuttle is that the setting of the hot oil relief can be confirmed or adjusted when the transmission is in neutral.

The two ports marked 1 are common as are the two marked 2. Therefore the assembly can be teed off the loop rather than being plumbed into the loop.

The two ports marked 1 are common as are the two marked 2. The high pressure relief that is physically on the same side as port 1 controls the pressure on port 2

and vice versa.

When the transmission is in neutral the charge pressure is controlled by the charge pump relief. When the hot oil shuttle opens, some or all of the charge pump

flow is redirected to the hot oil relief. The charge pump relief must be set higher than the hot oil relief to produce hot oil flow. The higher the differential pressure

between the 2 reliefs, the higher the hot oil flow. The amount of hot oil flow is determined by the pressure vrs flow curves of the 2 reliefs and is difficult to quantify.

The standard setting of the hot oil relief is 200 psi (14 bar) at a flow of 4 gpm (16 L/min).

Hydraulic motors leak. Therefore a mechanical brake is recommended to positively lock any stopped live load.

PRIMARY CARTRIDGE CONFIGURATION