Hydraulic Cylinder Standards
NFPA (US) and ISO/metric standard bore sizes, rod diameters, mounting style codes, and stroke limitations for hydraulic cylinders.
NFPA Standard Bore Sizes
| Bore (in) | Bore (mm) | Piston Area (in2) | Standard Rod Options (in) | Pressure Series |
|---|---|---|---|---|
| 1.50 | 38.1 | 1.767 | 0.625, 1.00 | Light, Medium, Heavy |
| 2.00 | 50.8 | 3.142 | 0.625, 1.00, 1.375 | Light, Medium, Heavy |
| 2.50 | 63.5 | 4.909 | 1.00, 1.375, 1.75 | Light, Medium, Heavy |
| 3.25 | 82.5 | 8.296 | 1.375, 1.75, 2.00 | Light, Medium, Heavy |
| 4.00 | 101.6 | 12.566 | 1.75, 2.00, 2.50 | Medium, Heavy |
| 5.00 | 127.0 | 19.635 | 2.00, 2.50, 3.00, 3.50 | Medium, Heavy |
| 6.00 | 152.4 | 28.274 | 2.50, 3.00, 3.50, 4.00 | Medium, Heavy |
| 7.00 | 177.8 | 38.485 | 3.00, 3.50, 4.00, 4.50 | Medium, Heavy |
| 8.00 | 203.2 | 50.265 | 3.50, 4.00, 4.50, 5.00 | Heavy |
| 10.00 | 254.0 | 78.540 | 4.50, 5.00, 5.50, 7.00 | Heavy |
| 12.00 | 304.8 | 113.097 | 5.50, 7.00, 8.00 | Heavy |
| 14.00 | 355.6 | 153.938 | 7.00, 8.00, 10.00 | Heavy |
Standard Rod Diameters (NFPA)
| Rod (in) | Rod (mm) | Rod Area (in2) | Compatible Bores (in) | Area Ratio Range |
|---|---|---|---|---|
| 0.625 (5/8) | 15.9 | 0.307 | 1.50, 2.00 | 1.21-1.11 |
| 1.000 (1) | 25.4 | 0.785 | 1.50, 2.00, 2.50 | 1.80-1.19 |
| 1.375 (1-3/8) | 34.9 | 1.485 | 2.00, 2.50, 3.25 | 1.90-1.22 |
| 1.750 (1-3/4) | 44.5 | 2.405 | 2.50, 3.25, 4.00 | 1.96-1.24 |
| 2.000 (2) | 50.8 | 3.142 | 3.25, 4.00, 5.00 | 1.61-1.19 |
| 2.500 (2-1/2) | 63.5 | 4.909 | 4.00, 5.00, 6.00 | 1.64-1.21 |
| 3.000 (3) | 76.2 | 7.069 | 5.00, 6.00, 7.00 | 1.56-1.22 |
| 3.500 (3-1/2) | 88.9 | 9.621 | 5.00, 6.00, 7.00, 8.00 | 1.96-1.24 |
| 4.000 (4) | 101.6 | 12.566 | 6.00, 7.00, 8.00 | 1.80-1.33 |
| 4.500 (4-1/2) | 114.3 | 15.904 | 7.00, 8.00, 10.00 | 1.70-1.25 |
| 5.000 (5) | 127.0 | 19.635 | 8.00, 10.00 | 1.64-1.33 |
| 5.500 (5-1/2) | 139.7 | 23.758 | 10.00, 12.00 | 1.43-1.27 |
| 7.000 (7) | 177.8 | 38.485 | 10.00, 12.00, 14.00 | 1.96-1.33 |
ISO/Metric Standard Bore Sizes
| Bore (mm) | Bore (in) | Piston Area (cm2) | Standard Rod Options (mm) |
|---|---|---|---|
| 25 | 0.98 | 4.91 | 12, 14, 16 |
| 32 | 1.26 | 8.04 | 14, 16, 18, 20 |
| 40 | 1.57 | 12.57 | 18, 20, 22, 25 |
| 50 | 1.97 | 19.63 | 22, 25, 28, 32, 36 |
| 63 | 2.48 | 31.17 | 28, 32, 36, 40, 45 |
| 80 | 3.15 | 50.27 | 36, 40, 45, 50, 56 |
| 100 | 3.94 | 78.54 | 45, 50, 56, 63, 70 |
| 125 | 4.92 | 122.72 | 56, 63, 70, 80, 90 |
| 160 | 6.30 | 201.06 | 70, 80, 90, 100, 110 |
| 200 | 7.87 | 314.16 | 90, 100, 110, 125, 140 |
| 250 | 9.84 | 490.87 | 110, 125, 140, 160, 180 |
| 320 | 12.60 | 804.25 | 140, 160, 180, 200, 220 |
Common Area Ratios
| Area Ratio | Rod/Bore Ratio | Characteristics | Typical Applications |
|---|---|---|---|
| 2:1 | 0.707 | Equal extend/retract speed, equal regenerative force | Press cylinders, equal speed circuits |
| 1.5:1 | 0.577 | Faster retract, good general purpose | Machine tools, material handling |
| 1.33:1 | 0.500 | Heavy rod, high column strength | Long stroke push applications |
| 1.25:1 | 0.447 | Maximum rod strength | High buckling load applications |
Where D = bore diameter, d = rod diameter
NFPA Mounting Style Codes
Cap End Mounts
MF1 Head Rectangular Flange
Rectangular flange at head end. Fixed mounting, absorbs side loads. Common for press applications.
MF2 Cap Rectangular Flange
Rectangular flange at cap end. Fixed mounting with thrust absorbed at cap. Most rigid mounting.
MF5 Head Square Flange
Square flange at head end. Alternative to MF1 for different mounting patterns.
MF6 Cap Square Flange
Square flange at cap end. Alternative to MF2 for different mounting patterns.
Side Mounts
MS2 Side Lug Mount
Lugs on both sides of head. Allows centerline mounting. Good for moderate side loads.
MS4 Side Tapped Mount
Tapped holes in sides. Simple mounting, allows adjustment. Not for heavy side loads.
MS7 Side End Lug
Lug mounts at head and cap ends. Distributes mounting loads along cylinder.
Pivot Mounts
MP1 Cap Clevis
Clevis (yoke) at cap end. Allows angular movement. Requires spherical rod bearing.
MP2 Cap Spherical Bearing
Spherical bearing in cap. Self-aligning, absorbs misalignment. Premium mounting.
MP3 Cap Eye
Eye (lug) at cap end. Simple pivot mount with external pin. Economical design.
MP4 Cap Detachable Clevis
Removable clevis bracket. Allows field interchangeability of mounting style.
MP5 Cap Detachable Eye
Removable eye bracket. Modular design for flexible installation options.
MP6 Cap Detachable Spherical Bearing
Removable spherical bearing bracket. Combines alignment capability with modularity.
Trunnion Mounts
MT1 Head Trunnion
Trunnion pins at head end. Allows pivot about fixed axis. Common for loader arms.
MT2 Cap Trunnion
Trunnion pins at cap end. Pivot mount with thrust at cap bearing.
MT3 Intermediate Fixed Trunnion
Trunnion at intermediate position, non-adjustable. For specific leverage requirements.
MT4 Intermediate Adjustable Trunnion
Trunnion position adjustable along barrel. Allows tuning of pivot point location.
Tie Rod Mounts
MX0 No Tie Rod Extensions
Standard tie rod length. Base configuration for flange or other mounting.
MX1 Head Tie Rod Extension
Extended tie rods at head end for through-bolt mounting to structure.
MX2 Cap Tie Rod Extension
Extended tie rods at cap end. Common for simple fixed mounting.
MX3 Both End Tie Rod Extension
Extended tie rods at both ends. Maximum mounting flexibility.
Rod End Connection Styles
| Code | Style | Description | Applications |
|---|---|---|---|
| NF | Male Thread | External threads on rod end | Most common, with jam nut |
| NT | Female Thread | Internal tapped hole in rod | Compact, threaded attachment |
| RE | Rod Eye | Eye (lug) machined on rod | Pin connection, allows pivot |
| RC | Rod Clevis | Clevis fork machined on rod | Yoke connection, larger pins |
| RB | Rod Ball Joint | Spherical ball on rod end | Self-aligning, angular motion |
| RF | Rod Flange | Flanged end on rod | Bolted connection, fixed |
| RP | Plain Rod | Unthreaded rod extension | Special machined attachments |
Stroke Limitations
| Bore (in) | Max Stroke - Push (Fixed Mount) |
Max Stroke - Push (Pivot Mount) |
Stop Tube Required Above |
|---|---|---|---|
| 1.50 - 2.50 | 24 in (610 mm) | 36 in (914 mm) | 18 in (457 mm) |
| 3.25 - 4.00 | 36 in (914 mm) | 60 in (1524 mm) | 24 in (610 mm) |
| 5.00 - 6.00 | 60 in (1524 mm) | 120 in (3048 mm) | 36 in (914 mm) |
| 7.00 - 8.00 | 96 in (2438 mm) | 144 in (3658 mm) | 48 in (1219 mm) |
| 10.00+ | 120 in (3048 mm) | 180 in (4572 mm) | 60 in (1524 mm) |
| Mounting Style | End Fixity Factor (K) | Column End Condition |
|---|---|---|
| Both ends fixed (flanges) | 0.5 | Guided both ends |
| One fixed, one guided | 0.7 | Fixed cap, guided rod |
| Both ends pinned | 1.0 | Pivot at both ends |
| One fixed, one free | 2.0 | Cantilever loading |
NFPA Pressure Series
| Series | Working Pressure | Construction | Applications |
|---|---|---|---|
| Light Duty | 1,500 psi (103 bar) | Thin wall, economy design | Clamping, low force applications |
| Medium Duty (Standard) | 2,500 psi (172 bar) | Standard industrial construction | General industrial, mobile |
| Heavy Duty | 3,000 psi (207 bar) | Heavy wall, large ports | Press, high force, demanding |
| Mill Type | 5,000 psi (345 bar) | Tie rod or welded, massive | Steel mills, heavy presses |