Accumulator Discharging and Charging Procedures {0738, 4263, 4264, 4331, 5077, 5077, 5081, 7474} Caterpillar

Accumulator Discharging and Charging Procedures {0738, 4263, 4264, 4331, 5077, 5077, 5081, 7474}

Usage:

Caterpillar Products: All

Introduction

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Table 1
Revision History
Revision	Summary of Changes
15	Changed to add bladder accumulator notice.
16	Changed add bladder accumulator advisory information.
17	Changed to add QR codes and Channel1 links.

The information in this instruction will provide the instructions for discharging and charging accumulators for Caterpillar machines. For accumulator information for tool attachment applications, refer to your tool manual for your specific application.

Safety Section

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Hydraulic circuits must be adequately bled of any residual pressure before proceeding with hydraulic repairs. Make sure adequate personal protective equipment (safety glasses, face shield, gloves) is being worn when initially disconnecting hydraulic fittings. Insure that there is no load resting on the circuit to prevent serious injury or death due to falling loads. Pressurized hydraulic fluid can penetrate the skin, resulting in serious illness or death.

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Pressurized System!
Hydraulic accumulators contain gas and oil under high pressure. DO NOT disconnect lines or disassemble any component of a pressurized accumulator. All gas pre-charge must be removed from the accumulator as instructed by the service manual before servicing or disposing of the accumulator or any accumulator component.
Failure to follow the instructions and warnings could result in personal injury or death.

Only use dry nitrogen gas to recharge accumulators. See your Cat dealer for special equipment and detailed information for accumulator service and charging.

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Dry nitrogen is the only gas approved for use in the accumulators. The charging of oxygen gas in an accumulator will cause an explosion. An explosion can be eliminated by using nitrogen gas cylinders with standard CGA (Compressed Gas Association, Inc.) No. 580 connectors. When nitrogen gas is ordered, make sure to order the cylinders with CGA No. 580 connectors.

Do not rely on color codes or other methods of identification to tell the difference between nitrogen and oxygen cylinders. In any application, never use an adapter to connect your nitrogen charging group to a valve outlet used on both nitrogen, oxygen, or other gas cylinders. BE SURE YOU USE DRY NITROGEN (99.8% purity).

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Personal injury or death can result from escaping fluid under pressure.
Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Always use a board or cardboard when checking for a leak.

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Personal injury can result from hydraulic oil pressure and hot oil.
Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.

Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine.
To prevent personal injury or death, perform the following:
Park the machine on a smooth, level surface.
Lower the work tool to the ground and engage the parking brake.
Stop the engine and remove the key.

Block the wheels and install the steering frame lock.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, PERJ1017, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat^® products. Dispose of all fluids according to local regulations and mandates.

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NOTICE

Discharging and charging bladder type accumulators must be done slowly to avoid damaging the bladder.

Note: Check each accumulator for nitrogen leakage at all potential leak points. A nitrogen leak is difficult to detect. A solution that consists of soap and water can be used to detect leaks. Make sure that there is no leakage around the gas valve base and at the top of the gas valve. Make sure that the gas valve caps are in place. Also, on piston accumulators, check the joint between the end caps and the shell as well as at the base of any other additional access ports that may have been added to the end caps.

Identification of Charging Valves

Identification of the charging valve is critical for safe discharging of the accumulator. Charging valves on Caterpillar equipment include the following types:

Type 1

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Illustration 1	g02729754

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Illustration 2	g03203036

This type of valve is a standard Schrader valve. This valve is opened by depressing a spring-loaded core (1) with the charging chuck of the nitrogen charging equipment.

Type 2

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Illustration 3	g02729772

This type of valve opens by turning a hex nut (2). The valve contains no core.

Type 3

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Illustration 4	g06351070

This is an ACP type valve that also contains a spring loaded core (3), similar to the Schrader valve. This valve is opened by depressing the spring-loaded core (3) with the charging chuck of the nitrogen charging element.

Type 4

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Illustration 5	g02730308

This type of valve is larger than the other three types and has 28 mm threads (5). This valve is opened by turning a screw (6) which is contained in the valve body.

Required Tools

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Illustration 6	g01624351
Tooling (D)

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Illustration 7	g02146997
Tooling (F)

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Illustration 8	g03330551
Tooling (D), Tooling (H), Tooling (J), and Tooling (K)

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Table 2
Tool	Item	Qty	Part No	Description
D			175-5507	Nitrogen Charging Group
	D1	1	8S-4600	Fitting
	D2	1	8S-1506	Coupling As
	D3	1	162-4147	Hose As
	D4	1	8S-4599	Coupling As
	D5	1	2S-5244	Fitting
	D6	1	1S-8937	Needle Valve
	D7	1	8T-0859	Pressure Gauge (0 to 25,000 kPa (0 to 3,600 psi))
	D8	1	162-4146	Regulator
	D9	1	7S-5106	Chuck
	D10	1	1S-8938	Chuck
	D11	1	1S-8941	Hose As
F			349-4200	Thermometer
H			9U-6740	Accumulator Charging Gp
H			152-2023	Nitrogen Charging Fitting Gp⁽¹⁾
J			334-1071	Adapter
K			9U-6741	Adapter

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⁽¹⁾	Recommended for Type 4 Valves

Accumulators with Type 1 Valve

Note: A CWS login is required to access Caterpillar Channel1. Scan the QR code below with a QR enabled devise or copy the link that follows.

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Illustration 9	g06404048

Reference: For more information, refer to "Type 1 & 3 Cat Accumulators" on Caterpillar Channel1.

https://channel1.mediaspace.kaltura.com/media/t/1_icud5x03

Bladder Accumulator Advisory

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Illustration 10	g06372850

Discharging and charging bladder accumulators needs to be done in a slow and controlled manner, otherwise there is a risk of explosive decompression (gas getting trapped in the bladder membrane during a rapid change in pressure) which can lead to bubbles in the bladder as shown in Illustration 10 causing weak points or rupture.

Discharge Procedure

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Table 3
Accumulators with Type 1 Valve
Tool	Item	Qty	Part No	Description
D			175-5507	Nitrogen Charging Group
	D1	1	8S-4600	Fitting
	D2	1	8S-1506	Coupling As
	D3	1	162-4147	Hose As
	D4	1	8S-4599	Coupling As
	D5	1	2S-5244	Fitting
	D6	1	1S-8937	Needle Valve
	D7	1	8T-0859	Pressure Gauge (0 to 25,000 kPa (0 to 3,600 psi))
	D8	1	162-4146	Regulator
	D9	1	7S-5106	Chuck
	D10	1	1S-8938	Chuck
	D11	1	1S-8941	Hose As
F			349-4200	Thermometer

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Illustration 11	g01624351
Tooling (D) 175-5507 Nitrogen Charging Group

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Illustration 12	g02730373
(7) Cap (8) Nitrogen charging valve (9) Core

Identify the correct nitrogen charging chuck.
Attach hose assembly (D11) to nitrogen charging chuck (D9) or (D10).
Turn valve handle of nitrogen charging chuck (D9) or (D10) all the way in the counterclockwise direction.
Note: Turning the valve handle will ensure that nitrogen charging valve (8) will not be opened when nitrogen charging chuck (D9) or (D10) is attached.
Remove cap (7) from the nitrogen charging valve (8).
Attach nitrogen charging chuck (D9) or (D10) to nitrogen charging valve (8).
Turn valve handle of nitrogen charging chuck (D9) or (D10) in the clockwise direction to open nitrogen charging valve (8). Turning the valve handle will release all the nitrogen from the accumulator through hose assembly (D11).

Testing and Charging Procedure for the Accumulator Precharge Pressure

Note: Test the accumulator precharge pressure when the machine is not running and all pressure has been released from the hydraulic system. Make certain that hydraulic pressure at the accumulator is at zero. At this point the piston will be bottomed at the hydraulic end. For information on releasing the system pressure, refer to the Operation and Maintenance Manual for the machine.

Remove cap (7) on nitrogen charging valve (8).
Identify the correct nitrogen charging chuck (D9) or (D10).
Turn the valve handle of nitrogen charging chuck (D9) or (D10) all the way in the counterclockwise direction.
Attach nitrogen charging chuck (D9) or (D10) and hose assembly (D11) to nitrogen charging valve (8).
Attach hose assembly (D11) between nitrogen charging chuck (D9) or (D10) and the tee. Install needle valve (D6) to the tee. Refer to Illustration 11. Install pressure gauge (D7) in the remaining open port on the tee.
Turn the valve handle for needle valve (D6) all the way in the clockwise direction. Completely turning the valve handle will ensure the needle valve (D6) is closed.
Turn valve handle of nitrogen charging chuck (D9) or (D10) in the clockwise direction to open nitrogen charging valve (8).
Read pressure gauge (D7) to determine the charge pressure in the accumulator. If charging is needed, attach regulator (D8) to a nitrogen tank.
Adjust pressure regulating screw on the regulator to obtain the correct pressure reading on the gauge. Refer to the Testing and Adjusting manual for your machine to obtain the correct pressure.
Note: If the machine has been running for some time, the temperature of the accumulator may be different from the ambient temperature of the outside air. Refer to the table in your machine Testing & Adjusting information for the proper pressure for your machine. Use tooling (F) to determine the current temperature of the accumulator.
Open needle valve (D6). Nitrogen will flow from the regulator to the accumulator. When gauge (D7) reads the correct pressure, close needle valve (D6).
Allow the temperature of the accumulator to stabilize. Recheck the precharge pressure at the stabilized temperature.
Once the accumulator is charged, turn the valve handle of chuck (D9) or (D10) counterclockwise completely. Remove chuck (D9) or (D10). Remove the regulator from the nitrogen tank.

Accumulator Charge Procedure for a Rebuilt Piston Type Accumulator

When the accumulator has been rebuilt, the air must be removed from the upper nitrogen chamber of the accumulator. Using hydraulic oil can help to remove the air from the upper nitrogen chamber of the accumulator and to lubricate the top seal of the piston in the accumulator. The piston within the accumulator is typically cupped on the nitrogen side. Fill the upper nitrogen chamber of the accumulator with enough hydraulic oil to cover the top of the piston.

After the installation of the rebuilt accumulator is complete, use the following steps to charge the accumulator.

Identify the correct nitrogen charging chuck.
Attach hose assembly (D11) to nitrogen charging chuck (D9 or D10).
Turn the valve handle of nitrogen charging chuck (D9 or D10) all the way in the counterclockwise direction.
Note: Turning the valve handle will ensure that nitrogen charging valve (8) will not be opened when nitrogen charging chuck (D9 or D10) is attached.
Remove cap (7) from nitrogen charging valve (8).
Attach nitrogen charging chuck (D9 or D10) to nitrogen charging valve (8).
Turn the valve handle of nitrogen charging chuck (D9 or D10) in the clockwise direction to open nitrogen charging valve (8).
Start the engine and allow the engine to run until the engine is warm. Activate the system for the accumulator.
Hydraulic oil will flow into the bottom of the accumulator. The air will first be forced out of the upper chamber of the accumulator through the test equipment. Then, the hydraulic oil will be forced out of the upper chamber of the accumulator through the test equipment. Remove as much of the hydraulic oil using this method and with the help of gravity if possible. When the hydraulic oil stops flowing out of the top of the accumulator, the upper chamber of the accumulator will contain little to no air. It is acceptable for a small amount of air to remain inside the nitrogen side of the accumulator.
Note: A small amount of hydraulic oil will remain inside the accumulator. The small amount of hydraulic oil on the nitrogen side is acceptable and will help with lubrication.
Charge the accumulator according to the procedure in "Testing and Charging Procedure for the Accumulator Precharge Pressure". Rebuilt accumulators require longer charging times. New accumulators require less charging time. When the accumulator has been rebuilt, the piston is located in the top of the cylinder. The piston will be forced to the bottom of the cylinder during the charging procedure.

Accumulators with Type 2 Valve

Note: A CWS login is required to access Caterpillar Channel1. Scan the QR code below with a QR enabled devise or copy the link that follows.

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Illustration 13	g06404060

Reference: For more information, refer to "Type 2 Cat Accumulators" on Caterpillar Channel1.

https://channel1.mediaspace.kaltura.com/media/t/1_a54f2xqk

Bladder Accumulator Advisory

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Illustration 14	g06372850

Discharge Procedure

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Table 4
Accumulators with Type 2 Valve
Tool	Item	Qty	Part No	Description
D			175-5507	Nitrogen Charging Group
	D1	1	8S-4600	Fitting
	D2	1	8S-1506	Coupling As
	D3	1	162-4147	Hose As
	D4	1	8S-4599	Coupling As
	D5	1	2S-5244	Fitting
	D6	1	1S-8937	Needle Valve
	D7	1	8T-0859	Pressure Gauge (0 to 25,000 kPa (0 to 3,600 psi))
	D8	1	162-4146	Regulator
	D9	1	7S-5106	Chuck
	D10	1	1S-8938	Chuck
	D11	1	1S-8941	Hose As
F			349-4200	Thermometer

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Illustration 15	g01624351
Tooling (D) 175-5507 Nitrogen Charging Group

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Illustration 16	g02730534
(10) Cap (11) Hex nut (12) Nitrogen charging valve

Identify the correct nitrogen charging chuck.
Attach hose assembly (D11) to nitrogen charging chuck (D9) or (D10).
Turn the valve handle of nitrogen charging chuck (D9) or (D10) all the way in the counterclockwise direction.
Remove cap (10) from nitrogen charging valve (12).
Attach nitrogen charging chuck (D9) or (D10) to nitrogen charging valve (12).
Hold nitrogen charging valve (12) with one wrench. Turn hex nut (11) with a second wrench in a counterclockwise direction.
Loosening the nut opens nitrogen charging valve (12). Three turns will fully open the valve. Opening the valve will release all the nitrogen from the accumulator through hose assembly (D11).

Testing and Charging Procedure for the Accumulator Precharge Pressure

Remove protective cap (10) on nitrogen charging valve (12).
Identify the correct nitrogen charging chuck (D9) or (D10).
Turn the valve handle of nitrogen charging chuck (D9) or (D10) all the way in the counterclockwise direction.
Attach nitrogen charging chuck (D9) or (D10) and hose assembly (D11) to nitrogen charging valve (12).
Attach hose assembly (D11) between nitrogen charging chuck (D9) or (D10) and the tee. Install needle valve (D6) on the tee. Refer to Illustration 15. Install pressure gauge (D8) in the remaining open port on the tee.
Turn the valve handle for needle valve (D6) all the way in the clockwise direction. Completely turning the valve handle will ensure the needle valve (D6) is closed.
Hold nitrogen charging valve (12) with one wrench. Turn hex nut (11) with a second wrench in a counterclockwise direction.
Loosening the nut opens nitrogen charging valve (12). Three turns will fully open the valve.
Read pressure gauge (D7) to determine the charge pressure in the accumulator. If charging is needed, attach regulator (D8) to a nitrogen tank.
Adjust pressure regulating screw on regulator (D8) to obtain the correct pressure reading on the gauge. Refer to the Testing and Adjusting manual for your machine to obtain the correct pressure.
Note: If the machine has been running for some time, the temperature of the accumulator may be different from the ambient temperature of the outside air. Refer to the table in your machine Testing & Adjusting information for the proper pressure for your machine. Use tooling (F) to determine the current temperature of the accumulator.
Open needle valve (D6). Nitrogen will flow from the regulator to the accumulator. When gauge (D7) reads the correct pressure, close needle valve (D6).
Allow the temperature of the accumulator to stabilize. Recheck the precharge pressure at the stabilized temperature.
Once the accumulator is charged, hold nitrogen charging valve (12) with one wrench. Turn hex nut (11) with a second wrench in a clockwise direction. Tightening the nut closes nitrogen charging valve (12). Remove chuck (D9) or (D10). Remove regulator (D8) from the nitrogen tank.

Accumulator Charge Procedure for a Rebuilt Piston Type Accumulator

After the installation of the rebuilt accumulator is complete, use the following steps to charge the accumulator.

Identify the correct nitrogen charging chuck.
Attach hose assembly (D11) to nitrogen charging chuck (D9) or (D10).
Turn valve handle of nitrogen charging chuck (D9) or (D10) all the way in the counterclockwise direction.
Remove cap (10) from nitrogen charging valve (12).
Attach nitrogen charging chuck (D9) or (D10) to nitrogen charging valve (12).
Hold nitrogen charging valve (12) with one wrench. Turn hex nut (11) with a second wrench in a counterclockwise direction.
Loosening the nut opens nitrogen charging valve (12). Three turns will fully open the valve.
Start the engine and allow the engine to run until the engine is warm. Activate the system for the accumulator.
Hydraulic oil will flow into the bottom of the accumulator. The air will first be forced out of the upper chamber of the accumulator through the test equipment. Then, the hydraulic oil will be forced out of the upper chamber of the accumulator through the test equipment. Remove as much of the hydraulic oil using this method and with the help of gravity if possible. When the hydraulic oil stops flowing out of the top of the accumulator, the upper chamber of the accumulator will contain little to no air. It is acceptable for a small amount of air to remain inside the nitrogen side of the accumulator.
Note: A small amount of hydraulic oil will remain inside the accumulator. The small amount of hydraulic oil on the nitrogen side is acceptable and will help with lubrication.
Charge the accumulator according to the procedure in "Testing and Charging Procedure for the Accumulator Precharge Pressure". Rebuilt accumulators require longer charging times. New accumulators require less charging time. When the accumulator has been rebuilt, the piston is located in the top of the cylinder. The piston will be forced to the bottom of the cylinder during the charging procedure.

Accumulators with Type 3 Valve

Note: A CWS login is required to access Caterpillar Channel1. Scan the QR code below with a QR enabled devise or copy the link that follows.

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Illustration 17	g06404048

Reference: For more information, refer to "Type 1 & 3 Cat Accumulators" on Caterpillar Channel1.

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Bladder Accumulator Advisory

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Illustration 18	g06372850

Discharge Procedure

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Table 5
Accumulators with Type 3 Valve
Tool	Item	Qty	Part No	Description
D			175-5507	Nitrogen Charging Group
	D1	1	8S-4600	Fitting
	D2	1	8S-1506	Coupling As
	D3	1	162-4147	Hose As
	D4	1	8S-4599	Coupling As
	D5	1	2S-5244	Fitting
	D6	1	1S-8937	Needle Valve
	D7	1	8T-0859	Pressure Gauge (0 to 25,000 kPa (0 to 3,600 psi))
	D8	1	162-4146	Regulator
	D9	1	7S-5106	Chuck
	D10	1	1S-8938	Chuck
	D11	1	1S-8941	Hose As
F			349-4200	Thermometer

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Illustration 19	g01624351
Tooling (D) 175-5507 Nitrogen Charging Group

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Illustration 20	g02730628
(13) Cap (14) Hex nut (15) Nitrogen charging valve

Identify the correct nitrogen charging chuck.
Attach hose assembly (D11) to nitrogen charging chuck (D9) or (D10).
Turn valve handle of nitrogen charging chuck (D9) or (D10) all the way in the counterclockwise direction.
Note: Turning the valve handle will ensure that nitrogen charging valve (15) will not be opened when nitrogen charging chuck (D9) or (D10) is attached.
Remove cap (13) from nitrogen charging valve (15). Attach nitrogen charging chuck (D9) or (D10) to nitrogen charging valve (15).
Hold nitrogen charging valve (15) with one wrench. Turn hex nut (14) with a second wrench in a counterclockwise direction.
Loosening the nut opens nitrogen charging valve (15). Three turns will fully open the valve.
Turn valve handle of nitrogen charging chuck (D9) or (D10) in the clockwise direction to open nitrogen charging valve (15). Loosening nut (14) and opening the valve will release all the nitrogen from the accumulator through hose assembly (D11).

Testing and Charging Procedure for the Accumulator Precharge Pressure

Remove protective cap (13) on nitrogen charging valve (15).
Identify the correct nitrogen charging chuck (D9) or (D10).
Turn the valve handle of nitrogen charging chuck (D9) or (D10) all the way in the counterclockwise direction.
Attach nitrogen charging chuck (D9) or (D10) and hose assembly (D11) to nitrogen charging valve (15).
Attach hose assembly (D11) between nitrogen charging chuck (D9) or (D10) and the tee. Install needle valve (D6) on the tee. Refer to Illustration 19. Install pressure gauge (D8) in the remaining open port on the tee.
Turn the valve handle for needle valve (D6) all the way in the clockwise direction.
Completely turning the valve handle will ensure the needle valve (D6) is closed.
Hold nitrogen charging valve (15) with one wrench. Turn hex nut (14) with a second wrench in a counterclockwise direction.
Loosening the nut opens nitrogen charging valve (14). Three turns will fully open the valve.
Turn valve handle of nitrogen charging chuck (D9) or (D10) in the clockwise direction to open nitrogen charging valve (15).
Read pressure gauge (D7) to determine the charge pressure in the accumulator. If charging is needed, attach regulator (D8) to a nitrogen tank.
Adjust pressure regulating screw on regulator (D8) to obtain the correct pressure reading on the gauge. Refer to the Testing and Adjusting manual for your machine to obtain the correct pressure.
Note: If the machine has been running for some time, the temperature of the accumulator may be different from the ambient temperature of the outside air. Refer to the table in your machine Testing & Adjusting information for the proper pressure for your machine. Use tooling (F) to determine the current temperature of the accumulator.
Open needle valve (D6). Nitrogen will flow from the regulator to the accumulator. When gauge (D7) reads the correct pressure, close needle valve (D6).
Allow the temperature of the accumulator to stabilize. Recheck the precharge pressure at the stabilized temperature.
Once the accumulator is charged, turn the valve handle counterclockwise completely. Hold nitrogen charging valve (15) with one wrench. Turn hex nut (14) with a second wrench in a clockwise direction. Tightening the nut closes nitrogen charging valve (15). Remove chuck (D9) or (D10). Remove the regulator from the nitrogen tank.

Accumulator Charge Procedure for a Rebuilt Piston Type Accumulator

After the installation of the rebuilt accumulator is complete, use the following steps to charge the accumulator.

Identify the correct nitrogen charging chuck.
Attach hose assembly (D11) to nitrogen charging chuck (D9) or (D10).
Turn valve handle of nitrogen charging chuck (D9) or (D10) all the way in the counterclockwise direction.
Remove cap (13) from nitrogen charging valve (15).
Attach nitrogen charging chuck (D9) or (D10) to nitrogen charging valve (15).
Hold nitrogen charging valve (15) with one wrench. Turn hex nut (14) in a counterclockwise direction with a second wrench. Loosening the hex nut (14) opens nitrogen charging valve (15). Three turns counterclockwise will fully open the valve.
Start the engine and allow the engine to run until the engine is warm. Activate the system for the accumulator.
Hydraulic oil will flow into the bottom of the accumulator. The air will first be forced out of the upper chamber of the accumulator through the test equipment. Then, the hydraulic oil will be forced out of the upper chamber of the accumulator through the test equipment. Remove as much of the hydraulic oil using this method and with the help of gravity if possible. When the hydraulic oil stops flowing out of the top of the accumulator, the upper chamber of the accumulator will contain little to no air. It is acceptable for a small amount of air to remain inside the nitrogen side of the accumulator.
Note: A small amount of hydraulic oil will remain inside the accumulator. The small amount of hydraulic oil on the nitrogen side is acceptable and will help with lubrication.
Charge the accumulator according to the procedure in "Testing and Charging Procedure for the Accumulator Precharge Pressure". Rebuilt accumulators require longer charging times. New accumulators require less charging time. When the accumulator has been rebuilt, the piston is located in the top of the cylinder. The piston will be forced to the bottom of the cylinder during the charging procedure.

Accumulators with Type 4 Valve

Note: A CWS login is required to access Caterpillar Channel1. Scan the QR code below with a QR enabled devise or copy the link that follows.

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Illustration 21	g06404072

Reference: For more information, refer to "Type 4 Cat Accumulators" on Caterpillar Channel1.

https://channel1.mediaspace.kaltura.com/media/1_q6wksybo

Bladder Accumulator Advisory

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Illustration 22	g06372850

Discharge Procedure

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Table 6
Accumulator with Type 4 Valve
Tool	Item	Qty	Part No	Description
D			175-5507	Nitrogen Charging Group
	D1	1	8S-4600	Fitting
	D2	1	8S-1506	Coupling As
	D3	1	162-4147	Hose As
	D4	1	8S-4599	Coupling As
	D5	1	2S-5244	Fitting
	D6	1	1S-8937	Needle Valve
	D7	1	8T-0859	Pressure Gauge (0 to 25,000 kPa (0 to 3,600 psi))
	D8	1	162-4146	Regulator
	D9	1	7S-5106	Chuck
	D10	1	1S-8938	Chuck
	D11	1	1S-8941	Hose As
F			349-4200	Thermometer
H			9U-6740	Accumulator Charging Gp
H			152-2023	Nitrogen Charging Fitting Gp⁽¹⁾
J			334-1071	Adapter
K			9U-6741	Adapter

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⁽¹⁾	Recommended for Type 4 Valves

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Illustration 23	g03330551
Tooling (D) 175-5507 Nitrogen Charging Group Tooling (H) Tooling (J) Tooling (K)

Note: The recommended accumulator charging group for Type 4 valves is 152-2023 Nitrogen Charging Fitting Gp. The 9U-6740 Accumulator Charging Gp may also be used for Type 4 valves. Sometimes, the threads on the tooling nut in 9U-6740 Accumulator Charging Gp are too long to have a proper seal. In such cases, the technician may need to add washers to the tooling nut in 9U-6740 Accumulator Charging Gp to create a proper seal.

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Illustration 24	g02713418
Detail of Tooling (H) ( H1) Tee handle (H2) Manual purge valve (H3) Cap nut (H4) Check valve

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Illustration 25	g02730659
(16) Cap (17) Vent Screw

Note: Make sure adequate personal protective equipment (safety glasses, face shield, hand gloves) is being worn prior to discharge or charge an accumulator.

Turn manual purge valve (H2) in the clockwise direction to close the purge valve.

Remove cap (16) from the charging valve.

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If the vent screw is loosened more than one quarter turn, the vent screw could become a projectile which could result in physical injury.

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NOTICE

Over-tightening vent screw (17) above 20 N·m (15 lb ft) can damage vent screw (17). Damage to vent screw (17) may not allow the tooling (H) to relieve accumulator pressure and required an extra procedure. Contact DSN for more details.

Ensure the vent screw (17) is completely closed.Do not over tighten.
Use a 6 mm (0.24 inch) Allen wrench to loosen vent screw (17) one quarter turn. Retighten vent screw (17) to one quarter turn with the fingers.
Attach tooling (H) to the charging valve.
Turn tee handle (H1) in the counterclockwise direction to open vent screw (17). Carefully open manual purge valve (H2). Release pressure slowly until the gas pressure is discharged.
Close the manual purge valve (H2).

Testing and Charging Procedure for the Accumulator Precharge Pressure

Note: Make sure adequate personal protective equipment (safety glasses, face shield, hand gloves) is being worn prior to discharge or charge an accumulator.

Before connecting the tooling, close manual purge valve (H2) on tooling (H). Turn manual purge valve (H2) in the clockwise direction to close manual purge valve (H2).
Before connecting the tooling, close needle valve (D6). Turn the needle valve handle in the clockwise direction to close the needle valve.
Assemble tooling (D), tooling (H), tooling (J), and tooling (K). Refer to Illustration 23.
Install regulator assembly (D8) on the nitrogen tank valve. Adjust the screw on regulator (D8) to set the appropriate charge pressure. Refer to the Test and Adjust manual for your machine to determine the appropriate charge pressure. Use thermometer tooling (F) to determine the correct temperature.

Remove cap (16) from the charging valve.

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If the vent screw is loosened more than one quarter turn, the vent screw could become a projectile which could result in physical injury.

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NOTICE

Over-tightening vent screw (17) above 20 N·m (15 lb ft) can damage vent screw (17). Damage to vent screw (17) may not allow the tooling (H) to relieve accumulator pressure and required an extra procedure. Contact DSN for more details.

Ensure the vent screw (17) is completely closed.Do not over tighten.
Use a 6 mm (0.24 inch) Allen wrench to loosen vent screw (17) one quarter turn. Retighten vent screw (17) to one quarter turn with the fingers.
Hand tighten cap nut (H3) to the charging valve.
Open needle valve (D6). Allow nitrogen flow to purge air from the lines through the purge valve. After the air is purged, close manual purge valve (H2). Close needle valve (D6)
Turn tee handle (H1) a maximum of three turns in the counterclockwise direction. The gauge on tooling (H) will show the gas precharge pressure.
Open the shutoff valve on the nitrogen tank. Slowly open needle valve (D6).
Precharge the accumulator slowly. Charging too quickly may damage the accumulator. When the desired pressure is reached, close needle valve (D6). Close the shutoff valve on the nitrogen tank.
Allow the temperature of the accumulator to stabilize, then recheck the pressure. When the desired pressure is reached, turn tee handle (H1) to close the charging valve.
Open needle valve (D6). Slowly open manual purge valve (H2) to allow pressure in the charging equipment to purge off. When no pressure remains in the lines, close manual purge valve (H2). Remove cap nut (H3) from the charging valve. Remove regulator (D8) from the nitrogen tank.

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NOTICE

Over-tightening vent screw (17) above 20 N·m (15 lb ft) can damage vent screw (17). Damage of vent screw (17) may cause improper to relieve accumulator pressure.
Use a to tighten vent screw (17) to a torque of 20 N·m (15 lb ft).
Install cap (16). Hand tighten cap (16).

Additional Information Regarding Type 4 Valve Accumulator Pre-Charge Pressure Adjustments

Check the accumulator for following two conditions:

The accumulator has existing pre-charge (accumulator is exhibiting either low-precharge or high-precharge condition):
1. When charging an accumulator that has an existing gas pre-charge or discharging an accumulator to lower pre-charge, allow 10 minutes after recharging for the gas temperature and pressure to stabilize and then recheck to ensure that pressure matches appropriate values.
The accumulator has no initial gas pre-charge (accumulator is exhibiting complete discharge condition):
1. Remove ring seal (A) from the accumulator gas valve assembly and replace with new 222-5765 Ring Seal. Lubricate the new ring seal with mineral oil before installing in the accumulator gas valve assembly.
  Note: Use a 6 mm (0.24 inch) Allen wrench to overcome the initial torque on the socket head cap screw to ensure proper engagement to the screw head. Refer to Illustration 26.
  Use a 6 mm (0.24 inch) Allen wrench (B) to tighten socket head cap screw (C) to a torque of 20 N·m (14.75 lb ft).
  Note: DO NOT over-torque above 20 N·m (14.75 lb ft).
2. When charging an accumulator that has no initial gas pre-charge, allow 20 to 30 minutes after recharging for the gas temperature and pressure to stabilize and then recheck to ensure that pressure matches appropriate values.

Accumulator Charge Procedure for a Rebuilt Piston Type Accumulator

After the installation of the rebuilt accumulator is complete, use the following steps to charge the accumulator.

Note: Make sure adequate personal protective equipment (safety glasses, face shield, hand gloves) is being worn prior to discharge or charge an accumulator.

Before connecting tooling, close needle valve (D6). Turn the valve handle in the clockwise direction to close the valve.
Assemble tooling (D), tooling (H), tooling (J), and tooling (K). Refer to Illustration 23.

Remove cap (16) from the charging valve.

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If the vent screw is loosened more than one quarter turn, the vent screw could become a projectile which could result in physical injury.

Show/hide table

NOTICE

Over-tightening vent screw (17) above 20 N·m (15 lb ft) can damage vent screw (17). Damage to vent screw (17) may not allow the tooling (H) to relieve accumulator pressure and required an extra procedure. Contact DSN for more details.

Ensure the vent screw (17) is completely closed.Do not over tighten.
Use a 6 mm (0.24 inch) Allen wrench to loosen vent screw (17) one quarter turn. Retighten vent screw (17) to one quarter turn with the fingers.
Hand tighten cap nut (H3).
Open manual purge valve (H2).
Start the engine and allow the engine to run until the engine is warm. Activate the system for the accumulator.
Hydraulic oil will flow into the bottom of the accumulator. The air will first be forced out of the upper chamber of the accumulator through the test equipment. Then, the hydraulic oil will be forced out of the upper chamber of the accumulator through the test equipment. Remove as much of the hydraulic oil using this method and with the help of gravity if possible. When the hydraulic oil stops flowing out of the top of the accumulator, the upper chamber of the accumulator will contain little to no air. It is acceptable for a small amount of air to remain inside the nitrogen side of the accumulator.
Note: A small amount of hydraulic oil will remain inside the accumulator. The small amount of hydraulic oil on the nitrogen side is acceptable and will help with lubrication.
Close manual purge valve (H2).
Charge the accumulator according to the procedure in "Testing and Charging Procedure for the Accumulator Precharge Pressure". Rebuilt accumulators require longer charging times. New accumulators require less charging time. When the accumulator has been rebuilt, the piston is located in the top of the cylinder. The piston will be forced to the bottom of the cylinder during the charging procedure.