Boost Unit
Series BLA
parker.com/pmde
2
Parker Hannifin
Pump and Motor Division
Trollhättan, Sweden
Catalogue MSG30-8224/UK
Boost units
BLA
Contents Page
General information ..........................................................3
Description .......................................................................3
Oil cooling .........................................................................3
Filter ..................................................................................4
Boost unit selection ..........................................................4
Boost pressure .................................................................5
Installation ........................................................................5
Line connection ...............................................................6
Reservoir ..........................................................................6
Valves ...............................................................................6
Ordering information ......................................................... 6
Available versions .............................................................6
Filter cartridges .................................................................6
Installation dimensions .....................................................7
Content
FAILURE OR IMPROPER SELECTION OR IMPROPER USE OF THE PRODUCTS DESCRIBED HEREIN OR RELATED ITEMS
CAN CAUSE DEATH, PERSONAL INJURY AND PROPERTY DAMAGE.
This document and other information from Parker-Hannifin Corporation, its subsidiaries and authorized distributors provide
product or system options for further investigation by users having technical expertise.
The user, through its own analysis and testing, is solely responsible for making the final selection of the system and components
and assuring that all performance, endurance, maintenance, safety and warning requirements of the application are met. The
user must analyze all aspects of the application, follow applicable industry standards, and follow the information concerning
the product in the current product catalog and in any other materials provided from Parker or its subsidiaries or authorized
distributors.
To the extent that Parker or its subsidiaries or authorized distributors provide component or system options based upon data or
specifications provided by the user, the user is responsible for determining that such data and specifications are suitable and
sufficient for all applications and reasonably foreseeable uses of the components or systems.
Offer of Sale
Please contact your Parker representation for a detailed ”Offer of Sale”.
WARNING – USER RESPONSIBILITY
3
Parker Hannifin
Pump and Motor Division
Trollhättan, Sweden
Catalogue MSG30-8224/UK
Boost unit
BLA
BLA_cross_ny.eps
Leif A./04-11-22
The BLA boost unit simplifies the building of closed or
semi-closed hydrostatic transmissions.
Main features are:
• Replacesconventionalchargepumpand
corresponding valves in many applications
• Allowspumpspeedsabovenormalselfpriming
speed.
• Suitableforsystemowratesto400l/min
• Includeslter
• Simpleconstruction-nomoving/wearparts
• Cost-effectiveinstallation
• Smalltanksize
• Helpsinbuildingalow-costhydrostatic
transmission.
Typical applications:
• Fandrives
• Propellerdrives
• Generatordrives
• Pumpdrives.
Description
In a closed circuit hydrostatic transmission, a charge
pump is normally included with the main pump, pro-
vidingmake-upuidwhichreplacespumpandmotor
volumetric losses. It also maintains sufficient pump inlet
pressure to avoid cavitation.
The BLA boost unit replaces the charge pump in many
applications, when the following conditions are met:
- Themax-to-minpumpowratiodoesnotexceed2:1
- System pressure changes gradually without frequent
and pronounced pressure peaks
- The line length between pump and boost unit is
relatively short.
There are two basic sizes of the BLA boost unit:
- BLA4(to160l/minpumpow)
- BLA6(to400l/min).
The main part of the unit is an aluminium housing with
a built-in nozzle and an injector; refer to the cross sec-
tion to the right.
Whenuidowsfromthemotoroutletportthrough
theunitandtothepumpinletport,theincreaseduid
velocity between the nozzle and injector creates a low
pressurezonecausingadditionaluidtobedrawnfrom
tank into the main circuit.
Also, pressure increases after the injector, allowing the
pump to be operated at speeds higher than the self-
primingspeed.The’boostpressure’increaseswithow
asshowninthediagrams(g.4,page5).
The housing includes ports that should be connected to
the pump and motor drain ports respectively.
Anadditionalbleed-offnozzledivertsapprox.10%of
themainowthroughthecartridgelterbeforebeing
directed to the tank.
Oil cooling
An oil cooler is usually required in the hydraulic system,
in order to remove the heat that is generated in the
maincircuit.Afull-owoilcoolershouldbeinstalladin
the return line between the motor and the boost unit;
refer to fig. 3, page 4.
Fig. 1. BLA boost unit cross section.
Injector From Nozzle
tank
To
pump
inlet
From
motor
outlet
Bleed-off
nozzle
To
filter
From filter
to tank
General information
4
Parker Hannifin
Pump and Motor Division
Trollhättan, Sweden
Catalogue MSG30-8224/UK
Boost units
BLA
1
9
2
3
5
6
8
BLA_4_schematic.eps
Leif A./04-11-22
BLA_6_schematic.eps
Leif A./04-11-22
1
2
6
7
4
9
3
5
1
5
3
6
8
9
2
BLA_install.eps
Leif A./04-11-22
Filter
The BLA boost unit is supplied with a standard spin-on
cartridgelter.Thepaperinsertprovidesa20µmnomi-
nalltration(³50µmabsoluteltration).
Cartridgesareavailableasspareparts(page6).
Forcontinuousoperation,anadditionalfull-owreturn
filter is usually required. It should be installed upstream
of the BLA unit; refer to the top schematic to the right.
1. Pump
2. Motor
3. Boost unit (with injector
 andnozzle)
5. Filter cartridge
6. Pressure relief valve
8. Full-owlter(when
 required)
9. Reservoir
Fig. 3. Circuit schematics (examples).
1. Pump
2. Motor
3. Boost unit (with injector
 andnozzle)
4. Oilcooler(whenrequired)
5. Filter cartridge
6. Pressure relief valve
7. Directional control valve
8. Full-owlter(when
 required)
9. Reservoir
Boost unit selection
The BLA 4 is available in four sizes with a max recom-
mendedowof40,63,100,and160l/min.Alteris
included.
TheBLA6isavailableinthefollowingsizes:250,350
and400l/min;italsoincludesalter.
Example
Select a suitable boost unit for a closed loop hydro-
statictransmissionthatutilizesanF11-19pumpat
4 000rpm;nominalowisapprox.76l/min.
AccordingtotheF11/F12brochure,therequired
inletpressureforanF11-19,operatingasapumpat
4 000rpm,is0.9barabsolute.
TheBLA4-100isselected(refertothemiddledia-
gram,g.4).Itwillsupplyabout1.7barboostpres-
sureatapprox.76l/min,providingamarginforline
losses between the boost unit and the pump.
NOTE: Theboostpressure(aftertheunit)isapprox.
half the pressure before the unit.
As an example, the up-stream pressure of a
BLA4-100atmax.ow(100l/min)isabout
6.5 bar.
Fig. 2. Boost unit installation (example).
Technical Information
5
Parker Hannifin
Pump and Motor Division
Trollhättan, Sweden
Catalogue MSG30-8224/UK
Boost unit
BLA
Installation_reservoir.eps
Leif A./04-11-22
Boost pressure
The diagrams in fig. 4 show max outlet pressure versus
owthroughthevariousboostunits.Thepressurein-
creaseobtainedathigherowsusuallycorrespondsto
the additional pump inlet pressure required at elevated
shaft speeds.
To avoid pump cavitation, the boost unit should be in-
stalled as close to the pump as possible. The pressure
at the pump inlet must not, under any operating condi-
tion, drop below the required pressure at a particular
pump speed.
Fig. 4. BLA pressure/ flow diagrams.
Installation
For proper functioning, the boost unit must be installed
well below the lowest oil level in the reservoir.
The BLA can either be bolted directly to the reservoir
side wall as shown below or connected separately with
piping or hoses.
An adapter plate, with mounting face and hole pattern
corresponding to that of the boost unit housing, should
be fabricated and welded in place. The sealing is ac-
complished with seal washers.
Thelteredoilowfromtheboostunitmustenterthe
reservoir as far away as possible from the inlet, and the
pipe must always be well below the lowest oil level.
Fig. 5. Boost unit/reservoir installation (example).
Seal washer
Pressure [bar]
Flow[l/min]
Pressure [bar]
Flow[l/min]
Pressure [bar]
Flow[l/min]
Adapter plate
welded to
the reservoir
Technical Information
4
3
2
1
0
20 30 40 50 60
BLA_pressure_flow.eps
Leif A./04-11-22
BLA 4-63BLA 4-40
4
3
2
1
0
40 80 120 160
BLA 4-160BLA 4-100
4
3
2
1
0
100 200 300 400
BLA 6-400
BLA 6-250
BLA 6-350
6
Parker Hannifin
Pump and Motor Division
Trollhättan, Sweden
Catalogue MSG30-8224/UK
Boost units
BLA
Line connection
When the boost unit is connected to the reservoir with
pipingorhoses,linelengthshouldnotexceed0.5m,
andtheinnerdiametershouldequalorexceed13mm(
1
/
2
”).
To avoid large pressure losses between the boost unit
and the pump inlet, the line should be as straight as
possible,nottoexceed0.5minlength.
The recommended, minimum inner diameter of the line
is shown in the following table.
Reservoir
The reservoir should be large enough to allow the oil to
beturnedoverin1.5to2min.Theoilwillthenbesuf-
ficiently de-aerated. The size of the reservoir normally
correspondsto15-20%ofthepumpow.
Asanexample,apumpowof75l/minrequiresares-
ervoirof10to15l.
Valves
A system pressure relief valve or directional control
valve should be connected as shown in figure 3
(page4).
The valve return must be connected to the boost unit
inlet (notdirectlytothereservoir).
NOTE: The drain lines from the pump and the motor
are also connected to the boost unit; refer to
the schematics and installation drawings on
page 4.
Ordering information
Example: BLA 6 - 250
Type: BLA 4 or 6
Size: BLA 4: 40, 63, 100 or 160
BLA 6: 250, 350 or 400
Technical Information
Available versions
Version Part no.
BLA4-40 73186
BLA4-40-X* 379 7824
BLA 4-63 73061
BLA4-100 73062
BLA4-160 73159
BLA6-250 73311
BLA6-350 3701097
BLA6-400 73312
*
X-Bleed-offnozzleplugged;BLA4
Filter cartridges
Version Part no.
BLA4-40,-63,-100 3517857
BLA4-160 73194
BLA6-250 73308
BLA6-350,-400 73309
Seal washers (forportsPEandPF)
Version Part no. Washer size
BLA4(alle) 943908
1
/
2
”
BLA6-250 944 252
3
/
4
”
BLA6-350,-400 944 498 1”
BLA 4
size
Inner dia.
[mm]
BLA 6
size
Inner dia.
[mm]
-40 13 -250 32
-63 20 -350 38
100 20 -400 38
-160 25
7
Parker Hannifin
Pump and Motor Division
Trollhättan, Sweden
Catalogue MSG30-8224/UK
Boost unit
BLA
BLA6_install.eps
Leif A./04-11-22
PEPA
PE
PC
PA PB
PD
PF
PC
PF
109
29
L
20*
56
45
46
9
100
R11 (x4)
4217
90
Ø11 (x4)
100
65
Ø93
35
15
BLA 6
BLA 4
* Additional space required
for filter replacement
* Additional space required
for filter replacement
Installation dimensions
Port sizes
(allareBSP)
Port BLA 4 BLA 6 Description
PA
3
/
4
” 1
1
/
4
” From motor outlet
PB
3
/
4
” 1
1
/
4
” From motor outlet
PC
3
/
8
”
3
/
4
” From pump and motor
drain ports
PD
3
/
8
”
3
/
4
”
PE
1) 1
/
2
” 1” From reservoir
PF
1) 1
/
2
”
3
/
4
” Return to reservoir
PG
1
/
2
”
3
/
4
” To cooler
PH
1
/
2
”
3
/
4
” From cooler
1)Countersunktoacceptsealwasher:
PE: BLA4 – Ø 29x2.4; BLA6 – Ø 44x2.9
PF: BLA4 – Ø 29x2.4; BLA6 – Ø 36x2.4
Weight
BLA size Weight [kg]
4-40,-63,-100 1.9
4-160 2.1
6-250 3.1
6-350,400 3.2
Dimension L
BLA size L [mm]
4-40,-63,-100 153
4-160 203
6-250 250
6-350,-400 301
Catalogue MSG30-8224/UK. POD 3/2018 TMCZ
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Ed. 2018-02-08
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