Flat Jacking

Contact Us

Flat Jacking Systems

Hydra-Capsule low height flat jacks range from 8 to 1,380 tonne capacity, the low height jack is capable of exerting extremely high trust forces. They are normally used within the civil and construction industry for a multitude of applications, such as, lifting heavy structures, stressing operations, transferring existing loads to temporary or permanent supports and permanently pre-loading buildings, structures, and bridge bearings to seismic isolators.

Due to their design, they are not only light in weight but require a minimal installation gap or just a few centimetres, when selecting a flat jack, the ideal working range should be about 75% of the jacks capacity

Permanent Units

Where a permanent force/load is require to a structure, flat jacks are installed in-situ and inflated using a high pressure injection system, epoxy resin or cementitious grout can be injected, but grout filled units are normally recommended in order to meet the current day environmental and fire regulations.

This application is primarily implemented whilst carry out works for pre-loading of structural steelwork or part of structural alterations, pre-stressing, underpinning and structural and bridge bearing pre-loading.

It’s essential that the mixing and grouting operation is carried out quickly and efficiently and we would therefore strongly recommend that our experienced Engineers carry out such operations as mistakes can prove to be expensive.

Hydra Capsule provide a full design, in-house manufacturing and flat jacking installation service offered throughout the UK and Internationally. Bespoke flat jacks can be manufactured for special applications.

Advantages:

Forces from 8 tonnes upto over 1,380 tonnes (offering the largest selection worldwide)

Measuring and control of induced thrust forces and loads

Load transfer

Balance force loading on double-stack flat jack arrangement

Access restraints for wedging and grouting of gap

Low height jack as small as 35mm gap

Idea for underpinning and pre-stressing

Can be use for temporary (hydraulic oil / water) and permanent (grout and resin) applications

3 different type and pipe arrangements (below image)

Circluar from 8 to 1380 tonnes Capacity

JACK
CODE
CAPACITY
(tons)
CLOSED HEIGHT OUTSIDE
DIAMETER
THRUST
DIAMETER
MAXIMUM
STROKE
MAXIMUM
PRESSURE
FLUID
LITRES
WEIGHT
(KGS)
Data
Sheet
FJ 12 80 32 120 75 25 150 bar 0.3 4 PDF
FJ 15 150 32 150 105 25 150 bar 0.5 8 PDF
FJ 17 200 32 170 125 25 150 bar 0.8 9 PDF
FJ 19 250 32 190 145 25 150 bar 1.1 10 PDF
FJ 22 400 32 220 175 25 150 bar 1.2 16 PDF
FJ 25 500 32 250 205 25 150 bar 1.3 19 PDF
FJ 27 600 32 270 225 25 150 bar 1.6 20 PDF
FJ 30 800 32 300 255 25 150 bar 1.9 23 PDF
FJ 35 1000 35 350 305 25 150 bar 2.6 26 PDF
FJ 38 1300 35 380 335 25 150 bar 3.1 27 PDF
FJ 42 1600 35 420 375 25 150 bar 3.6 29 PDF
FJ 45 1800 35 450 405 25 150 bar 4.1 30 PDF
FJ 48 2100 35 480 435 25 150 bar 4.7 32 PDF
FJ 52 2650 35 520 475 25 150 bar 5.7 36 PDF
FJ 56 3000 35 560 515 25 150 bar 6.2 38 PDF
FJ 60 3450 35 600 555 25 150 bar 7.4 43 PDF
FJ 67 4800 35 675 625 25 150 bar 9.6 59 PDF
FJ 69 4900 35 690 645 25 150 bar 10.5 67 PDF
FJ 75 6000 35 750 700 30 150 bar 12.4 90 PDF
FJ 75B 6000 45 750 700 50 150 bar 19.8 95 PDF
FJ 87 7640 35 870 825 30 150 bar 16.8 111 PDF
FJ 92 8680 35 920 875 30 150 bar 18.7 126 PDF
FJ 102 10300 40 1020 940 32 150 bar 24.4 175 PDF
FJ 108 13800 40 1080 1030 32 150 bar 28.1 195 PDF

Applications for flat jacking

Preloading of Steelwork and Load transfer

Excavation Struts, propping and shoring Jacking & Preloading

Lifting and Weighing

Settlement and Structural Jacking

Hydraulic to Permanent Transfusion

Bridge Deck Lifting and Bridge Bearing Preloading

Temporary Flat Jacks

When Flat jacks are required for a temporary duration and then subsequently removed, this operation is usually carried out with water or hydraulic oil fluid.

The benefits of temporary flat jacks:

Use as a load cell (pre-inflates), connected with a pressure gauge or digital transducer read-out

Continuous load monitoring and adjustment

Multiple flat jacks circuit

Ability to transfuse from temporary to permanent application (epoxy resin or cementitious grout

Transfusion Units

Single Flat Jack

Transfusion flat jacks are specially designed in-house, and manufactured by Hydra Capsule. These flat jacks have the ability to transfuse grout whilst under load, from a temporary to a permanent load. The design of the flat jacks allows for a balanced load and movement displacement throughout the grout transfusion operation.

Double-stack Flat Jacks

The same can be achieved as the double-stack flat jack arrangement. However, the transfusion method is inflating one flat jack, whilst the other flat jack is deflated and maintaining a constant balance load between both flat jacks.

Rectangle Flat Jack Systems

Hydra-Capsule Limited provides specialist rectangle flat jack systems for structural testing, controlled load application, masonry stress analysis and precision correction works.

Our flat jack solutions are used across heritage structures, bridge works, façade retention schemes and structural modification projects where controlled, uniform pressure must be applied within restricted spaces.

Designed for accuracy, reliability and minimal intrusion, rectangle flat jacks allow force to be introduced directly into structural elements without large-scale dismantling or disruption.

Rectangle flat jacks are thin, high-pressure hydraulic steel envelopes inserted into pre-cut slots within masonry, concrete or structural interfaces.

When pressurised, the flat jack expands vertically, applying a controlled and evenly distributed force to the surrounding structure.

Their slim profile makes them ideal for:

Masonry stress testing

Structural crack correction

Controlled load transfer

Bearing pressure verification/pre-loading

Compensation grouting interfaces

Applications

Structural Testing & Stress Measurement

Flat jacks are widely used for in-situ stress measurement within masonry and historic structures. By relieving and reapplying compressive stress, engineers can determine:

Existing compressive stress levels

Structural capacity

Load distribution behaviour

Residual stress conditions

This method is particularly valuable in refurbishment and conservation projects.

Square from 40 to 360 tonnes Capacity

JACK
CODE
CAPACITY
(KnS)
CLOSED HEIGHT OUTSIDE
DIAMETER
THRUST
DIAMETER
MAXIMUM
STROKE
MAXIMUM
PRESSURE
FLUID
LITRES
WEIGHT
(KGS)
Data
Sheet
SFJ20-20 400 35 200X200 155X155 25 140 bar 0.5 4 PDF
SFJ25-25 600 250X250 205X205 105 25 140 bar 0.5 8 PDF
SFJ30-30 900 35 300X300 255X255 25 140 bar 0.8 9 PDF
SFJ35-35 1600 35 400X400 355X355 25 140 bar 1.1 10 PDF
SFJ40-40 1600 35 400X400 355X355 25 140 bar 1.2 16 PDF
SFJ45-45 2000 35 450X450 405X405 25 140 bar 1.3 19 PDF
SFJ50-50 2500 35 500X500 445X445 25 140 bar 1.6 20 PDF
SFJ60-60 3600 35 600X600 555X555 25 140 bar 2.6 26 PDF

Rectangular from 50 to 500 tonnes Capacity

JACK
CODE
CAPACITY
(KnS)
CLOSED HEIGHT OUTSIDE
DIAMETER
THRUST
DIAMETER
MAXIMUM
STROKE
MAXIMUM
PRESSURE
FLUID
LITRES
WEIGHT
(KGS)
Data
Sheet
RFJ20-25 500 35 200X250 155X205 25 140 bar 0.3 4 PDF
RFJ25-30 750 250X300 205X255 105 25 140 bar 0.5 8 PDF
RFJ30-35 1050 35 300X350 255X305 25 140 bar 0.8 9 PDF
RFJ33-38 1250 35 330X380 285X335 25 140 bar 1.1 10 PDF
RFJ38-43 1600 35 380X430 335X385 25 140 bar 1.2 16 PDF
RFJ43-48 2050 35 430X480 385X435 25 140 bar 1.3 19 PDF
RFJ48-53 2550 35 480X530 435X485 25 140 bar 1.6 20 PDF
RFJ53-58 3050 35 530X580 485X535 25 140 bar 2.6 26 PDF
RFJ58-63 3650 35 580X630 535X585 25 140 bar 2.9 31 PDF
RFJ63-68 4250 35 630X680 585X635 25 140 bar 3.3 36 PDF
RFJ68-73 500 35 680X730 635X685 25 140 bar 3.6 41 PDF

GIVING CONSTRUCTION OUR SUPPORT

Contact Us

© Copyright 2026 Hydra-Capsule Ltd