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Information on available spare parts:www.boschrexroth.com/spc

Steering unit

Type LAGC

Sizes 50 to 630Component series 1X and 2XNominal pressure 175 barMaximum flow 63 l/min

RE 14365/10.07Replaces: 07.03

Table of contents Features

Content Page

Features 1

Ordering code 2

Function, section 3

Variants 4 and 5

Functions in the steering circuit 5

Technical data, general 6

Technical data of hydraulic fluid with selection diagram 7

Technical data, hydraulic 8

Determination of steering moment 8

Dimensioning of steering cylinder and steering pump 9

Unit dimensions of type LAGC.../LAGC...LD 10

Unit dimensions of type LAGC... LDA.. 11

H6211_d

– LAGC steering units are used in hydraulic steering circuits ofvehicles and mobile machines with large axle loads and travelspeeds not exceeding 50 km/h.

– With the aid of a steering unit even heavy vehicles can easilybe steered. The absence of a mechanical connection betweenthe steering unit and steering axle allows the designer to re-alize solutions, which would be impossible with conventionalsteering systems.

– The steering unit includes all valves required in the hydraulic

steering circuit for the protection of the steering unit and thesteering cylinder. This eliminates the need for additional pipe-work.

– If the hydraulic pump fails, vehicles can also be steered manu-ally with the help of the LAGC; in this case, the LAGC acts ashand pump for the steering cylinder.



2/12 Bosch Rexroth AG Hydraulics LAGC RD 14365/10.07

Ordering code

Steering unitDesign

with integrated valves = C

Displacement (cm3/rev)

Noise characteristics Standard 3) = –

Low 4) = N

Series

Series 10 to 19 = 1X

(10 to 19: Unchanged installation

and connection dimensions)

Series 20 to 29 = 2X 5)

(20 to 29: Unchanged installation

and connection dimensions)

– = Special specifications

Please consult our salesorganization

6) Pipe ports

P, T, L, R / LD

01 = Pipe thread toDIN 3852

06 = Metric ISO thread toDIN 3852

12 = UNF thread to SAE

40 = Metric ISO thread toDIN 3852

Seals

M = Suitable for mineral oil (HL, HLP)to DIN 51524 and fast bio-degradablehydraulic fluids (HETG, rape seed oil) to

VDMA 24568(see RE 90221)

7) Pressure relief valve setting

(pressure differential)

90 = 90 bar

140 = 140 bar

175 = 175 bar

7) Shock valve setting

(pressure differential)

150 = 150 bar200 = 200 bar

240 = 240 bar

Reaction

No code = Without reaction

R = With reaction

Load Sensing

No code = Without load signal in Open Center(OC) variant

LD = Dynamic load signal

LDA = Dynamic load signal, can be flanged on

LAG C M *

Frame size OC; LD R1); LDA2)

50 = 50

63 = 63

80 = 80

100 = 100

125 = 125

160 = 160

200 = 200

250 = 250

320 = 320

400 = 400

500 = 500

630 = 630

= Standard product range

= Extended product range

1) With reaction

2) Dynamic load signal, can be flanged on3) To be specified for LD variant4) To be specified for Open Center (OC) variant5) Only Open Center design (extended flow: see Technical

data - page 8)6) For thread dimensions, see Unit dimensions on pages 10

and 117) The response pressure of shock valves must be 50 bar

higher than the setting of the pressure relief valve, but notexceed 2.2 times the setting of the latter (see §38 StVZO,German Road Traffic Licensing Regulation).

Preferably: 150 to 90; 200 to 140; 240 to 175.

Order example:

1. LAGC 200 -1X/LD150-90M01

Steering unit with integrated valves

Frame size 200, dynamic load signal

Shock valves 150 bar, pressure relief function 90 bar

Pipe ports P, T, L, R in G 1/2 , LD in G 1/4

2. LAGC 200 N1X/150-90M01

Steering unit with integrated valves

Frame size 200, low noise characteristics

Shock valves 150 bar, pressure relief function 90 bar

Pipe ports P, T, L, R in G 1/2



Hydraulics Bosch Rexroth AGRD 14365/10.07. LAGC 3/12

Function, section

Pilot spool (1) of the control valve is rotated via the steering col-umn in relation to control sleeve (2). This opens a cross-sectionbetween the spool and the sleeve. The pressure oil acts on ro-tor set (3) and sets the latter into motion. The oil is then fed viathe rotor set to the steering cylinder. The rotation of the rotor

acts on the sleeve, which then follows the rotary movement ofthe spool.

The size of the opened cross-section depends on the turningspeed of the steering wheel and on the steering pressure; onLoad-Sensing variants, it depends exclusively on the turningspeed.

If the steering movement is interrupted and the spool is at astandstill, the oil, which still flows through the open cross-sec-tion to the rotor, causes the rotor and hence the sleeve to con-tinue to rotate.

The rotary movement then causes the cross-section to close- now, the rotor also comes to a standstill and, at the same

time, the steering cylinder is in the required position. Centeringspring (4) brings and holds the spool and sleeve in a neutral po-sition to each other.

Pressure relief valve (5) limits the system pressure of the steer-ing circuit. On the Load-Sensing variants, the pilot valve for the

load signal is installed instead (see sectional drawing).Two shock valves (6) protect ports L and R to the steering cyl-inder. If one of the shock valve responds, the discharged oil isfed via anti-cavitation valve (7) to the opposite side, or missingleak-oil aspired from the tank.

In the event of an oil supply failure, the LAGC operates as handpump. In this operational state, oil can be withdrawn from thetank via anti-cavitation valve (8), with check valve (9) preventingair to be aspired via the pump port (P). During normal opera-tion, this valve prevents shocks on the steering wheel causedby excessive external steering forces.

3

7

1

4

2

5

6

8

9

1 Pilot spool

2 Control sleeve

3 Rotor set

4Centering spring

5 Pressure relief valve

6 Shock valve

7 Anti-cavitation valve

8 Anti-cavitation valve

9Check valve




Standard variant

Open Center with Non Reaction = OC / NR

Mainly used in steering systems with fixed displacement hydrau-lic pumps.

When no steering movement is performed, the connection be-tween pump port (P) and tank port (T) is open (OC), and thepump flow is directed to the tank almost at zero pressure. PortsL1) (left) and R1) (right) are blocked in the neutral position. Inthis way, external forces acting via the steering cylinder are sup-ported without the driver perceiving any resulting reaction forc-es on the steering wheel (Non Reaction).

1) Contrary to standardization, the actuator lines in steeringsystems are usually designated “L” and “R”, not “A” and “B“.

Standard variant

Open Center with Reaction = OC / R

In the neutral position, the cylinder ports are connected witheach other. External forces acting via the steering cylinder areperceived as reaction force by the driver on the steering wheel(Reaction). When the driver releases the steering wheel afterthe steering maneuver is completed, the wheels and the steer-ing wheel automatically return to straight-ahead travel, providedthat the steering geometry is suitable for this.

Load-Sensing variants

Steering units with Load Sensing provide a load signal that canbe used for controlling a priority valve and/or a pump. They aredesigned as Closed-Center steering systems, with the connec-tion of pump port (P) to tank port (T) being closed in the neutralposition.

If the steering system and working hydraulics are supplied by acommon pump, a priority valve must be installed. This valve en-sures the preferred supply of the steering unit with oil, with thevalve being controlled by the load signal of the steering unit. Ifno steering movement is performed, the entire oil flow from thepump is available to the working hydraulics. Fixed or variabledisplacement pumps can be used as hydraulic pump.

TP

L R

TP

RL

TP

L R

TP

RL

TP

L R

LD

RL

TP

LD

Device variants




Device variants

Load signal, dynamic

The oil flowing in the load signal line transmits the load signal,with the pilot oil flowing from the priority valve to the steeringunit. Also in the neutral position, a continuous, low pilot oil flowof ca. 0.5 l/min is provided. Consequently, the steering unit hasapproximately the same temperature as the oil.

Thermal shocks are largely prevented.

The LD variant causes the priority valve to react faster. Thehard point at the beginning of the steering movement is usuallyno longer perceivable- even under cold start conditions.

Flanged-on priority valve

Steering units with flanged-on priority valve significantly reducethe piping effort.

Low-noise variant

Steering units of the LAGC Open Center variant are generallydelivered in the low-noise variant “N“.

Functions in the steering circuit

LAGC of LD variant for flanged-on priority valve

Servo-operation

Steering units of type LAGC consist of a manually operatedservo-valve of rotary spool design, a rotor set, which operatesaccording to the gerotor principle, and the required valves forthe steering circuit.

The frame size of the rotor set determines the oil volume, whichflows per steering wheel turn to the steering cylinder. The frame sizeof the rotor set is selected so that with 3 to 5 turns of the steeringwheel, it is possible to steer from one limit stop to the other.

Emergency operation

During normal operation of the steering unit, when the hydraulicoil displaces a sufficient amount of oil, the torque on the steer-ing wheel is less than 5 Nm. In the event of a hydraulic pumpfailure, the steering unit operates in the emergency mode; therotor set acts as hand pump, and the vehicle is steered manual-ly, without power assistance. The pressure that can be generat-ed manually depends on the frame size of the rotor set and theforce applied to the steering wheel. The smaller the rotor set,

the higher the pressure that can be built up manually.

M steer Frame size 050 063 080 100 125 160

120 Nm p in bar 90 85 80 60 50 40

70 Nm p in bar 52 50 46 35 30 23

M steer Frame size 200 250 320 400 500 630

120 Nm p in bar 30 25 20 15 12 10

70 Nm p in bar 17 14 11 8 7 6

If a higher pressure is required for steering in emergency op-

eration at 70 Nm, a steering unit with reduction gear, LAGU toRE 11867 or LAGZ to RE 11868, can be installed.

Pressure relief valve

The pressure relief valve is available with three settings:

90 bar; 140 bar; 175 bar

Note!

The pressure in the T-line adds to the set pressure.

Shock and anti-cavitation valves

These valves, which are installed in the LAGC on the cylinderside, are available with three settings:

150 bar; 200 bar; 240 bar

Anti-cavitation valve

In the event of a hydraulic pump failure, this valve, which is in-stalled between the P and the T port, re-aspires hydraulic fluidfrom the tank.Check valve

This valve, which is installed in the P port prevents:

• oil from returning from the steering cylinder into the hydrau-lic system when the cylinder pressure becomes higher thanthe system pressure due to travel obstructions. Steeringshocks onto the steering wheel are therefore largely sup-pressed.

• air from being aspired via the P port in emergency operation.

L P T RLD

Attention!

Emergency operation is not intended for continuous op-eration!

During manual steering, the following pressures can beachieved in dependence upon the steering moment:

L P TLD R




Technical data (for applications outside these parameters, please consult us!)

General

Nominal pressure p bar 175

Ambient temperature range ϑ °C –20 to +80

Hydraulic fluid see below

Hydraulic fluid temperature range ϑ °C –20 to +80Viscosity range ν mm2/s 10 to 800

Permissible maximum degree of contami-nation of the hydraulic fluidCleanliness class to ISO 4406 (c) Class 19/16/13 1)

Steering moment - standard 2) M Nm ≤ 5

Steering moment - emergency operation M Nm ≤ 160 permissible

Max. tightening torque formounting screws

M T Nm 30 - see RE 11874 “Steering column“

1) The cleanliness classes specified for components must be adhered to in hydraulic systems.Effective filtration prevents malfunction and, at the same time, prolongs the service life of components.For the selection of filters, see data sheets RE 50070, RE 50076, RE 50081, RE 50086, RE 50087 and RE 50088.

2) Other steering moment variants (e.g. “low”) on request




Hydraulic fluids

Before carrying out engineering, please refer to the extensive in-formation on the selection of hydraulic fluids and operating con-ditions in our data sheets RE 90220 (mineral oil) and RE 90221(environmentally friendly hydraulic fluids). These data sheets

refer to axial piston units, but can also be applied by analogy tosteering units. In the case of hydraulic fluids, which require FPMseals, please consult us.Operating viscosity

We recommend that the operating viscosity (at operating temper-ature) be selected within the range of

νopt = optimum operating viscosity range of 16 to 46 mm2/s

referred to temperature, which is optimal in terms of efficiencyand service life.

Limiting viscosity

For limiting conditions, the following values are valid:

νmin = 10 mm2

/s at a permissible max. temperature ofϑ max = 80 °C

νmax = 800 mm2/s

Temperature range: (cf. selection diagram)

ϑ min = –20 °C

ϑ max = 80 °C

If temperature differences of more than 20 °C between thesteering unit and the hydraulic fluid are to be expected, either aLD or LDA variant or an Open-Center variant should be instal ledto warm up the steering unit.

Explanation regarding the selection of the hydraulic fluid

For the selection of the right hydraulic fluid, the operating tem-perature and the ambient temperature must be known.

The hydraulic fluid should be selected so that the operating vis-cosity ν

opt

is within the optimum range at operating tempera-ture (see selection diagram).

We recommend that the next higher viscosity class be selected.

Example: At an ambient temperature of X °C, the tank temper-ature reaches 60 °C. Within the optimum viscosity range, thiscorresponds to viscosity classes VG 46 or VG 68; the class tobe selected is: VG 68.Filtration of the hydraulic fluid

The finer the filtration, the better the cleanliness class achievedfor the hydraulic fluid, and the longer the service life of thecomplete hydraulic system.

Technical data of the hydraulic fluid

Note!To ensure functional reliabilty of the steering unit, at least thecleanliness classes specified for the hydraulic fluid are re-quired.

5

10

40

60

20

100

200

400600

10001600

νopt.

16

46

5

1600

V G 2 2

V G 3 2

V G 4 6

V G 6 8

V G 1 0 0

Selection diagram

Hydraulic fluid temperature range

V i s i c o s i t y i n m

m 2 / s

Temperature




Technical data, hydraulic

Steering unit

Type

Displacement

cm3

Flow Permissible max. pressure in port

Nom1)

l/min

max.2)

l/min

P

bar

T

bar

L and R

bar

LAGC 050 50 5.0 15 175 20 240

LAGC 063 63 6.3 20 175 20 240

LAGC 080 80 8.0 25 175 20 240

LAGC 100 100 10.0 30 175 20 240

LAGC 125 125 12.5 35 175 20 240

LAGC 160 160 16.0 50 175 20 240

LAGC 200 200 20.0 50 175 20 240

LAGC 250 250 25.0 50 175 20 240

LAGC 320 320 32.0 63 175 20 240

LAGC 400 400 40.0 63 175 20 240

LAGC 500 500 50.0 63 175 20 240

LAGC 630 630 63.0 63 175 20 240

1) Referred to a steering velocity of 100 steering turns /min.2) Max. flow for the variant “Open Center, low noise“, series 1X = 40 l/min (values for Standard centering spring

package)

Calculation of the steering moment

Formula symbols

A = required cylinder area [mm2]

A1 = cylinder piston area, single-rod cylinder [mm2]

A2 = annulus cylinder area, single-rod cylinder [mm2]

b = tire width [mm]

d = piston rod diameter [mm]

D = cylinder diameter [mm]

e = distance swivel bearing - center of tire [mm]

F = steering force [N]

F A = steering axle load [N]

h = cylinder stroke length [mm]i = number of steering wheel turns

l = smallest, effective steering leverage [mm]

M = steering moment [Nm]

n = steering speed [min–1]

nidle = motor idling speed [min–1]

nmotor = operating speed of motor [min–1]

p = steering pressure [bar]

qvp = pump flow [l/min]

V = displacement of steering unit [cm3/rev]

V P = displacement of steering pump [cm3/rev]

V CYL = cylinder volume [cm3

]μ = friction coefficient

Steering mo-ment

h

l

b

e

M

Steeringforce

M = 0.05 • F A • • • [Nm]1

1+eb

0.7b

200

F = • 103 [N]M

I




Steering pump

The pump should be dimensioned so that at idling speed of themotor, a steering speed of approx. 50 min–1 can be achieved.Depending on the steering wheel diameter, the maximum steer-ing speed is ca. 100 to 150 min–1.

Pump flowqVP = V • (n +10) • 10–3 l/min.

The pump displacement ( frame size) required for steering atidling speed and at operating speed of the vehicle must be cal-culated.

Dimensioning of steering cylinder and steering pump

Note!

Further information on suitable steering columns can be found

in RE 11874, and on associated priority valves for steering sys-tems in load signal circuits in RE 27548.

For general information, see RE 64020-B1.

Product-specific instructions in RE 07015-B2.

If a single-rod cylinder or a double-rod cylinder are used, A2 must be greater than the required cylinder area.If two cross-connected single-rod cylinders are used, A1+A2 must be greater than the required cylinder area.

The frame size of the steering unit is calculated from the cylin-der volume and the desired number of steering wheel turns.

Cylinder volume

Steering cylinder

Required cylinder area

Cylinder area (piston side)

Cylinder area (piston rod side)

A =F

• 10 p[mm2]

A1 =π

• D2

4[mm2]

A2 =π

• (D2–d 2)4

[mm2]

V =V ZYL

i [cm3/rev]

The usual number of steering wheel turns is 3 to 5 from limitstop to limit stop.

V P =qVP • 103

nidle

Frame size of the pump at operating speed

[cm3/rev]V P = qVP • 103

nMotor

[cm3/rev]

Frame size of the pump at idling speed

Displacement LAGC

V ZYL = A • h103

[cm3]




44

l 1

l 2

60

1 5

m i n .

T L

RP

6 , 3

2 , 8

3 0 ± 1

M10; 15

4 4

80 +3

59

8

0 + 3

M10; 16

3/8-16 UNC; 16 2)

L

R

LD

34 ±0,5

6 3 ± 0 , 5

1)

Unit dimensions: Type LAGC... / LAGC...LD... (dimensions in mm)

Port Variant d1 Ød2 Ød4 b min. a1 a2α

01 G 1/2 – 28+0.4 14 max. 0.2 – –

P, T, L, R 06 M18x1 .5 19.8+0.1 29+0.4 14.5 max. 0.2 2.4 +0.4 15° ±1°

12 3/4-16 UNF 20.6+0.1 30+0.5 14.3 max. 0.2 2.4+0.4 15° ±1°

40 M18x1.5 – 25+0.4 12 max. 0.2 – –

01 G 1/4 – 25+0.4 12 1 ±0.5 – –

LD 06 M12x1 .5 13.8+0.1 25+0.4 11.5 1 ±0.5 2.4+0.4 15° ±1°

12 7/16-20 UNF 12.4+0.1 21+0.5 11.5 1 ±0.5 2.3+0.4 12° ±1°

40 M12x1.5 – 25+0.4 12 1 ±0.5 – –

1) LD bore on variant LAGC...LD...2) Only with variant 12 (see pipe ports)

Imperial, metric thread

d1

Ød4

b a 1

Gear hub profile 16/32Diametral pitch to

ANS B921-1970

Note!

Variants LAGC...LDA.. are not covered by this table. For more de-

tails, see page 11.

d1

α

b a 1

a 2

d4

d2

UNF, metric - thread

Frame size l1 l2

050 125 6.8

063 127 8.3

080 129 10.5

100 132 13.2

125 135 16.5

160 139 21.1

200 145 26.4

250 151 33.0

320 161 42.3

400 172 52.9

500 186 68.0

630 202 83.3




l 1

l 2

60

Ø25,4

1 5 m i n .

T L

RP

L

R

3 0 ± 1

6 , 3

2 , 8

44

LD

M10; 15

80 +3

Ø 8 8 + 3

59

8 0 + 3

Ø 8 2 ± 0 ,3

M10; 16

Ø44,4

4 4

Unit dimensions: Type LAGC...LDA.. (dimensions in mm)

Gear hub 16/32

Diametral pitch to

ANS B921-1970

Frame size l1 l2

050 125 6.8

063 127 8.3

080 129 10.5

100 132 13.2125 135 16.5

160 139 21.1

200 145 26.4

d1

Ød4

b a 1

Port Variant d1 Ød2 Ød4 bmin. a1

P, T, L, R 40 M18x1.5 – – 12 –

Metric thread



Bosch Rexroth AGHydraulicsZum Eisengießer 197816 Lohr am Main, GermanyPhone +49 (0) 93 52 / 18-0Fax +49 (0) 93 52 / 18-23 [email protected]

© This document, as well as the data, specifications and otherinformation set forth in it, are the exclusive property of BoschRexroth AG. It may not be reproduced or given to third partieswithout its consent.The data specified above only serve to describe the product.No statements concerning a certain condition or suitability for acertain application can be derived from our information. The in-formation given does not release the user from the obligation of

own judgment and verification. It must be remembered that ourproducts are subject to a natural process of wear and aging.


Bosch Rexroth AGMobile HydraulicsD-19370 ParchimLudwigsluster Chaussee 5Phone 0 38 71 / 60 60Fax 0 38 71 / 60 63 70 oder 60 62 01

Notes

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