Electric Drives Linear Motion and
and Controls Hydraulics Assembly Technologies Pneumatics Service
Power Unit Standard
Oil sight glass AB 31-21
ND 3 2005-12-09
Oil reservoir accessories replaces
AB 31-21 : 2003-06-26
Table of contents
1 Purpose................................................. 1
2 Area of application............................... 1
3 Responsibilities ................................... 1
4 Dimensions, weights and
assortments.......................................... 2
5 Technical Data/Resistance.................. 4
6 Type code ............................................. 4
7 Ordering example/match code ........... 4
© Bosch Rexroth AG 2003
8 Labels.................................................... 5
9 For other standards see ...................... 6
Changes
The following have been changed when compared with issue 2003-06-26: Editorially revised; Cross
references to other standards supplemented.
Previous Issues
1999-04-21, 2001-07-11, 2003-06-26
1 Purpose
Oil sight glasses to this standard are used for checking and monitorinig the fluid level and oil reservoir
temperature.
2 Area of application
This standard is valid within the Bosch Rexroth AG, Business Unit Industrial Hydraulics. Within the
Business Unit Industrial Hydraulics for all Product units, Factories, Regional centres, Foreign subsidiaries
and all subcontractors of the Business Unit Industrial Hydraulics.
ab-31-21-000_nor_n_en_2005-12-09
3 Responsibilities
Dept. BR/ESP1 is responsible for the creation/updating, Dept. BRH-SY/PRM1 is responsible for the
contents.
Bosch Rexroth AG created: BR/ESP1, Ewald Carmen / Knaub Karsten
Zum Eisengießer 1 • D-97816 Lohr am Main checked: BR/ESP, Ullrich Bettina
Tel. +49 9352 18-0 • Fax +49 9352 18-2917 released: BRH-SY/PRM1, Wiesmann Erhard
Page 1 / 6
Page 2 / 6
AB 31-21 : 2005-12-09 Oil sight glass, ND 3
4 Dimensions, weights and assortments
4.1 Oil sight glass nominal size 76 and 127
without thermometer with thermometer with
in the indicator tube probe thermometer 45
version T version FT200
5
32 32 20
1)
M12
l1±0,2
l2
l3
2) 3
Rexroth
X Rexroth
X
A C E 2
25,5
B D F
1
A-B C-D E-F
ø40
Section X
Rexroth
5 8
4 7 200
6 9
1) Marking for max. oil level Pos. 1: Reservior wall
2) Marking for min. oil level Pos. 2: Screw (clamping torque 8 Nm)
Pos. 3: Housing
Pos. 4: Flat gasket ∅27x3
Pos. 5: O-ring 12,3x2,4
Pos. 6: Thermometer T
Pos. 7: Connection pipe
Pos. 8: Indicator tube
Pos. 9: Thermometer FT 200
Table 1
Standard (NBR) Special (FKM)
Dimensions Weight
DN Designation: Oelstandanzeiger AB31-21/...
in kg
l1 l2 l3 Material no. Material no.
076 R900029368 076V ---
76 76 108 34 0,20
076T R900033725 076TV ---
127 R900007824 127V R900002958
127 127 159 76 127FT200 R900023620 127FT200V R900027088 0,25
127T R900013663 127TV R900027086
Page 3 / 6
Oil sight glass, ND 3 AB 31-21 : 2005-12-09
4.2 Oil sight glass nominal size 254
without thermometer with thermometer with probe thermometer
in the indicator tube version FT200
version T
3)
l1
l3
l2
4)
Rexroth
X Rexroth
X
25,5
Section X
3) Marking for max. oil level
4) Marking for min. oil level
Rexroth
Table 2
Standard (NBR) Special (FKM)
Dimensions Weight
DN Designation: Oelstandanzeiger AB31-21/...
in kg
l1 l2 l3 Material no. Material no.
254 R900023618 254V R900027085
254 254 268 203 254FT200 R900023621 254FT200V R900027089 0,30
254T R900023619 254TV R900027087
Page 4 / 6
AB 31-21 : 2005-12-09 Oil sight glass, ND 3
5 Technical Data/Resistance
Table 3
Version
Oil sight glass
Standard (NBR) Special (FKM)
Item 3: Housing aluminium/steel
Item 2: Screw steel
Item 7: Connection pipe plastic/PA
Item 8: Indicator tube plastic/PA
Item 4: Item 4:
Seal NBR
Item 5: Item 5:
Reservoir excess pressure max. 1 bar
Pressure fluid temperature -20 °C to +80 °C
Thermometer in indicator tube/indicator range +20 °C to +80 °C
Probe thermometer 200 mm/indicator range 0 °C to +100 °C
Resistance:
Mineral oil HL/HLP to DIN 51524 resistant ---
Watery solutions HFC resistant ---
Phosphoric ester HFD-R to VDMA 24317 --- resistant
Organic ester HFD-U --- resistant
Triglyceride (rape seed oil) HETG resistant ---
Synthetic ester HEES to VDMA 24568 --- resistant
Polyglycols HEPG --- resistant
6 Type code
Example: Oelstandanzeiger AB31-21 / 127 FT200 V
AB standard
Nominal size (screw centres)
76 = 76
127 = 127
254 = 254
Thermometer
Without = no des.
Thermometer in indicator tube (°C and °F) =T
Probe thermometer 200 mm (°C and °F) = FT200
Media resistance (seal)
Standard (NBR) = no des.
Special (FKM) =V
7 Ordering example/match code
Oil sight glass, nominal size 127, with thermometer in indicator tube and use for mineral oil HLP:
OELSTANDANZEIGER AB31-21/127T Material no. R900013663
Page 5 / 6
Oil sight glass, ND 3 AB 31-21 : 2005-12-09
8 Labels
8.1 Label min./max.
ø13
30
max.
20
max. 5)
10
5)
20
Rexroth
min.
min.
6)
6)
5) Marking for max. oil level
6) Marking for min. oil level
Material: Al 0,5 mm
Table 4
Designation: Schild Material no.
AB31-21/min. R900026428
AB31-21/max. R900026429
Label is clamped under the hollow screw.
Page 6 / 6
AB 31-21 : 2005-12-09 Oil sight glass, ND 3
8.2 Label Indicating Oil Content of Reservoirs from AB 40-40 to AB 40-44
3
ø1
7)
max.
127
147
127
8)
min.
12
40 9)
7) Oil content specification for max. oil level
8) Oil content specification for min. oil level
9) Label is clamped under the hollow screw
Material: Al 1 mm
Table 5
Label AB 31-21
Reservoir
AB 40-40 - AB 40-44 Oil content
specification Designation: Schild ... Material no.
NG min. max.
100 70 90 AB31-21/ 100L-SKALA R900710546
160 115 150 AB31-21/ 160L-SKALA R900710550
250 180 230 AB31-21/ 250L-SKALA R900710554
400 285 365 AB31-21/ 400L-SKALA R900710555
630 490 595 AB31-21/ 630L-SKALA R900710556
800 620 755 AB31-21/ 800L-SKALA R900710557
1000 10) 640 960 AB31-21/1000L-SKALA R900710547
10) Label for upper and lower oil level indication consists of two pieces
9 For other standards see
AB 40-.. Reservoir
DIN 51524 Pressure fluids; hydraulic oils
VDMA 24317 Fluid technology; hydraulics; flame-resistant gases; guidelines
VDMA 24568 Fluid technology; fast biologically degradable pressure fluids; minimum technical
requirements
