Stack-Mounting Counterbalance Valve, NG 6

max

= 80l/min,p

max

= 350bar

pilot operated, poppet type

Series SNSA…

1/5

Reference: 300-P-360101-EN-01

Issue: 06.2023

S Controlled movement of negative loads

S Controls the oil leaving the actuator (counterbalance

function)

S Load holding via leak-free poppet valve

S Secondary relief protection for the actuator

S For plate mounting valve, Interface NG 6 to

ISO 4401-03-02

1 Description

Counterbalance valves prevent actuator “runaway” in the

event of negative loads. The flow leaving the actuator (the

A line in the example) is piloted and controlled by the flow

entering the actuator (the B line), ensuring a cavitation-free

lowering of the load, as long as the valve pressure setting

is not exceeded (see application example). A counterbal

ance valve must be capable of holding the load without leak

age. The design of this valve is based on a pilot assisted

pressure relief valve (see pressure settings). The pressure

in the actuator inlet line causes the relief valve in the actua

tor outlet line to open. The level of pilot pressure which is re

quired is determined by the valve's pilot area ratio and by the

pressure generated by the load itselfs (see pressure set

tings).

To ensure a reliable secondary relief function (e.g. for ther

mal expansion) the related directional valve must have a

centre condition in which ports A and B are connected to

Tank T (spool type function G).

2 Symbol

3 Technical data

General characteristics Description, value, unit

Designation stack-mounting counterbalance valve

Design pilot operated, poppet type

Mounting method stack-mounting

Size NG 6, interface ISO 4401-03-02

Weight SNSA-A .. / -B ..-6 = 1.25 kg

SNSA-AB ..-6 = 1.50 kg

Mounting attitude unrestricted

Flow direction see symbols

Maximum operating pressure 350 bar

300-P-360101-EN-01/06.2023

Series SNSA

2/5

Description, value, unitGeneral characteristics

Adjustment change pressure range N1

pressure range N2

pressure range M1

pressure range M2

140…350 bar (pilot ratio 4.5:1)

70…280 bar (pilot ratio 3:1)

70…175 bar (pilot ratio 4.5:1)

30…105 bar (pilot ratio 3:1)

Opening pressure via check valve standard

on request

ca. 1.7 bar

ca. 0.3 bar

Hydraulic fluid HL and HLP mineral oil to DIN 51 524;

for other fluids, please contact BUCHER

Hydraulic fluid temperature range -25°C … +80°C

Viscosity range 10 … 300 mm

/s (cSt)

Maximum flow rate 80l/min

Surface corrosion protection all exposed parts with zinc-nickel plating

Minimum fluid cleanliness

Cleanliness class to ISO 4406:1999

class 20/18/15

4 Application example and pressure settings

5 Performance graphs

300-P-360101-EN-01/06.2023

Series SNSA

3/5

6 Dimensions & sectional view

7 Schematic section

showing the relevant ports

Seal kit Nr. DS-241

It. Qty. Qty. Qty. Description Size

1 4 2 2 O-ring Nr. 017 ∅ 17.17 x 1.78 N90

2 2 1 1 O-ring Nr. 015 ∅ 14.00 x 1.78 N90

3 4 4 4 O-ring Nr. 012 ∅ 9.25 x 1.78 N90

4 2 1 1 Backup ring 017

5 2 1 1 Backup ring 016

6 2 1 1 Backup ring 015

SNSA-A-6

SNSA-B-6

SNSA-AB-6...

300-P-360101-EN-01/06.2023

Series SNSA

4/5

8 Installation information

ATTENTION!

Maintenance work may only be carried out care

fully by qualified personnel. When mounting the

valve, make sure that the connection hole pattern

matches that of the mating surface. (Do not mix up

the connection side and the valve side). When re

placing seals, make sure that the seals are well

oiled or greased. The function cartridge must be

mounted with the specified tightening torque.

9 Ordering code

S = stack valve

N = counterbalance valve

S = poppet type

A … Q = standard model per current data sheet

Z … R = special features by arrangement on request

A = function A

B = function B

AB = function in A and B

6 = Nominal size 6

S = screw adjustment

N1 = pressure range 140 … 350 bar (normal version, standard design)

pilot ratio 4.5:1

N2 = pressure range 70 … 280 bar (on request)

pilot ratio 3:1

M1 = pressure range 70 … 175 bar (medium version, standard design)

pilot ratio 4.5:1

M2 = pressure range 30 … 105 bar (on request)

pilot ratio 3:1

= valves are shipped with pressure set at the maximum for the

specified pressure range e.g. if N1, then 350 bar

18 = check valve opening pressure 1.7 bar (standard)

03 check valve opening pressure 0.3 bar (on request)

(blank) = NBR (nitril-butadien-rubber / BUNA) seals (standard)

V = FKM (fluorocarbon rubber / VITON) seals

(special seals - please consult BUCHER)

Ex.

6 _

––

–

SAB

–

ASN

IMPORTANT!

Two check valve cracking pressures are avail

able. Use the 25 psi (1.7 bar) check unless actua

tor cavitation is a concern.

300-P-360101-EN-01/06.2023

Series SNSA

5/5

10 Related data sheets

Reference Description

400-P-030101 Interface NG 6 to ISO 4401-03-02

E 2023 by Bucher Hydraulics AG Frutigen, CH-3714 Frutigen

www.bucherhydraulics.cominfo.ch@bucherhydraulics.com

Data is provided for the purpose of product description only, and must not be construed as warranted characteristics in the legal sense. The

information does not relieve users from the duty of conducting their own evaluations and tests. Because the products are subject to continual

improvement, we reserve the right to amend the product specifications contained in this catalogue.

Classification: 430.305.300.305.305