Goodman Jack
Applications
The Goodman Jack is a borehole tool used for estimating the deformability of rock masses in-situ. It is designed to be used in 3″ (76 mm) boreholes.
Two models are available: a twelve piston model for use in hard rock, and a three-piston model for determining the consolidation-time properties of soft rock, soil, and stiff clays.

Operation
The Goodman Jack consists of a hydraulic jack with curved bearing plates, LVDT sensors, a displacement indicator, a hydraulic pump with pressure gauge, hydraulic hose, electrical cable, and a coupler for drill rod.
The jack is attached to drill rod and inserted into the borehole. A hand pump is used to create hydraulic pressure in the lines connected to the jack, which in turn activates the pistons and produces a uniform and unidirectional stress field at the bearing plate. The applied hydraulic pressure is measured with a standard Bourdon-type pressure gauge. The deformation of the rock is measured by two linear variable differential transformers (LVDT) and data are displayed by the indicator at the surface. After the test, the bearing plates are retracted by reversed pistons and the jack is withdrawn from the borehole.
The modulus of deformation is calculated using formulae derived empirically from in-situ testing and correction factors that were developed by laboratory testing.
For more information
Please download the datasheet and manual for the Goodman Jack. It can be viewed and printed with Adobe Acrobat Reader.
Goodman Jack Specifications
HARD ROCK JACK | |
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Number of Pistons | 12 |
Max Bearing Pressure | 64,000 kPa (9,300 psi) |
Maximum Force | 703 kN (158,100 lbf) |
Borehole Size | 76 mm, 3" nominal |
Minimum Diameter | 70 mm (2.75") |
Maximum Diameter | 83 mm (3.25") |
Linearity | ±0.5% for range of 73.7 to 78.7 mm (2.9 to 3.1"), ±1% for range of 72.4 to 80 mm (2.875 to 3.15") |
Maximum Hydraulic Pressure | 69,000 kPa (10,000 psi) |
Operating Temp | -32 to 60 °C (-25 to 140 °F) |
Temp. Coefficient | ±(0.04% Reading + 0.02% FS) per °C. ±(0.02% Reading + 0.01% FS) per °F |
Dimensions | 70 x 445 mm (2.75 x 17.5") |
Weight | 15 kg (33 lb) |
SOFT ROCK JACK | |
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Number of Pistons | 3 |
Max Bearing Pressure | 38,200 kPa (5,540 psi) |
Maximum Force | 419 kN (94,200 lbf) |
Borehole Size | 76mm, 3" nominal |
Minimum Diameter | 70 mm (2.75") |
Maximum Diameter | 83 mm (3.25") |
Linearity | ±0.5% for range of 73.7 to 78.7 mm (2.9 to 3.1"), ±1% for range of 72.4 to 80 mm (2.875 to 3.15") |
Maximum Hydraulic Pressure | 69,000 kPa (10,000 psi) |
Operating Temp | -32 to 60 °C (-25 to 140 °F) |
Temp. Coefficient | ±(0.04% Reading + 0.02% FS) per °C. ±(0.02% Reading + 0.01% FS) per °F |
Dimensions | 70 x 445 mm (2.75 x 17.5") |
Weight | 15 kg (33 lb) |
DISPLACEMENT INDICATOR | |
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Display | Dual LCDs with 3-digit signed values |
Operating Time | 10 hours with fully charged batteries |
Battery Charger | Internal from 115/230 VAC or 10-15 VDC |
Temp. Coefficient | ±(0.015% Reading +0.001% F.S.) per °C. ±(0.008% Reading +0.0006% F.S.) per °F. |
Operating Temp | -18 to 49°C (0 to 120 °F) |
Resolution | 0.01 mm with Metric Indicator. 0.001" with English Indicator |
Dimensions | 280 x 230 x 180 mm (11 x 9 x 7") |
Weight | 5 kg (11 lb) |
HAND PUMP | |
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Hydraulic Pump | Enerpac P-84 |
Maximum Pressure | 69,000 kPa 10,000 psi |
Pressure Gauge | 50 psi (345 kPa) resolution with accuracy of ±0.5% FS |
Dimensions | 690 x 180 x 150 mm (27 x 7 x 6") |
Weight | 13 kg (29 lb). Hose and cable add 10 kg per 15 m (22 lb per 50’) |
PART NUMBERS | ||
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Goodman Jack, Hard Rock | 52100100 | Hydraulic borehole probe for in situ tests in hard rock. Includes two LVDT displacement transducers, waterproof electrical connector, two selfsealing hydraulic quick-connectors, and threaded BX adapter |
Goodman Jack, Soft Rock | 52100200 | Hydraulic borehole probe for in situ tests in soft rock. Includes two LVDT displacement transducers, waterproof electrical connector, two selfsealing hydraulic quick-connectors, and threaded BX adapter |
Displacement Indicator | English Unit | 52102700 |
Metric Unit | 52102710 | |
Electrical Cable Assembly | 52100500 | Shielded, multi-conductor cable, waterproof connectors on each end, 15 m (50’) |
Hydraulic Hose Assembly | 52100600 | High Pressure Hydraulic Hose, 1/4-inch (6.4 mm.) I.D., double steel wire braid, SAE 100R2 Type A, with self-sealing quick-connectors each end, 50 ft (15 m) |
Hydraulic Pump, Model P-84 | 52100700 | Two-stage, 10,000 psi (70 MPa), with selector valve |
Hydraulic Tee Assembly | 52100800 | Includes three self-sealing quick-connectors for easily connecting hydraulic hose, pressure gauge and hydraulic pump |
Pressure Gauge, Model 200 | 52100900 | Bourdon-type, 4.5" diameter gauge with accuracy of 0.5% and twin tip pointer to eliminate reading errors. Range: 10,000 psi (70 MPa). Other ranges available on request |
Hydraulic Oil, HF-101 | 52102400 | Note: Carriers require surcharge and separate documents for air shipments of hydraulic oil |
Carrying Case, For Jack | 52101500 | Wooden carrying case for shipping and storage of Goodman Jack and accessories |
Carrying Case, For Pump | 52101501 | Wooden carrying case for shipping and storage of pump and accessories |