SMC CG1BN40-100 Round Body Air Cylinder 40 mm Bore

A short round-body standard cylinder

CG1BN40-100 is a standard-type, double-acting, single-rod air cylinder from the SMC CG1 series. It has a round tube, so it can be fitted with simple foot, flange, trunnion or clevis brackets, and it is made shorter than the older series it replaces: the catalogue says the overall length is 17 to 28 mm less than the SMC CA2 for the 40 to 63 mm bores.

The code reads CG1 (series), B (basic style; L is axial foot, F rod-side flange, G head-side flange, U and T are trunnion styles, D is clevis), N (the cushion type: rubber bumper; A would be air cushion), 40 (the 40 mm bore) and 100 (the 100 mm stroke). With no thread letter the ports are Rc, and with no suffix the rod end is plain, without a boot.

Technical specifications

Choosing between rubber bumper and air cushion

The N type has a rubber bumper at both ends. It is a simple, economical stop and is suitable for light loads and moderate speeds. The A type adds an air cushion that slows the piston before the end of the stroke, and the catalogue adds about 0.02 kg to the weight of the 40 mm size. For heavy loads at high speed, the air cushion or an external shock absorber is the better option. Check the allowable kinetic energy tables in the catalogue before you decide.

The cylinder can also take a rod boot in nylon tarpaulin (J, up to 70 deg C) or in heat-resistant tarpaulin (K, up to 110 deg C) for dusty or hot surroundings.

Mounting and accessories

The rod end nut is standard on every mounting style, and the clevis style includes a clevis pin. Single and double knuckle joints, a pivot bracket and a rod boot are options. For the 40 mm bore, trunnion styles are listed, but they are not offered for the 80 and 100 mm bores. Because the cylinder is compact, check the length drawings in the catalogue before replacing another series, to avoid a clash with the rest of the machine.

Please use clean, dry air and avoid side loads on the rod; a floating joint or a clevis mounting handles misalignment.

Documents and quotation

The SMC CG1 catalogue PDF below has the how-to-order page, specifications, weights, stroke tables and dimensions. Please confirm mounting style, cushion type, stroke, thread and switch needs before ordering. More cylinders are listed under Pneumatic Cylinders. Seven Star LLC is an independent supplier and quotes the exact code on request.

CG1BN40-100 in the Current CG1-Z Series

SMC now publishes the round-body CG1 cylinder as the CG1-Z series, and the current ordering codes end in a Z suffix. The how-to-order page also adds a mounting code Z (basic, with trunnion mounting female thread) alongside B (basic, without trunnion mounting female thread). SMC points out that this thread arrangement differs from the earlier product, so if a trunnion may be added later, choose the Z mounting. Our team can help confirm the correct ordering code when you replace an existing CG1BN40-100 on a machine.

Because the 40 mm bore can be disassembled, its rod seal, piston seal and tube gasket can be replaced with the seal kit. SMC states that bores of 50 mm and larger cannot be disassembled.

How the CG1BN40-100 Double-Acting Cylinder Works

In a double-acting cylinder, compressed air drives the piston in both directions. Air supplied to the head-side port pushes the piston and rod out over the 100 mm stroke while the rod-side port exhausts. Reversing the supply retracts the rod. The rubber bumpers (the N in the code) absorb the impact at each end of the stroke. As a guide, the theoretical extending force is the piston area multiplied by the pressure. For a 40 mm bore at 0.5 MPa, that is about 1257 mm² × 0.5 MPa ≈ 628 N, a calculated value before friction losses. The retracting force is lower because the rod reduces the effective area. Most designers apply a load factor of about 50 to 70% of the theoretical force for dynamic duty.

Selection & Ordering Guide

• Mounting: B or Z basic, L axial foot, F rod flange, G head flange, U rod trunnion, T head trunnion, D clevis. Brackets are shipped with the cylinder but are not assembled.
• Cushion: N rubber bumper, or A air cushion for higher kinetic energy.
• Rod end: male thread as standard; F gives a female rod end, for which no rod-end bracket is available.
• Rod-end brackets: V single knuckle joint, W double knuckle joint (with pin).
• Rod boot: J nylon tarpaulin or K heat-resistant tarpaulin.
• Auto switches: order the CDG1 version with a magnet and the required switch model and quantity.
• Made to order: examples include -XB6 heat-resistant (to 150°C), -XB7 cold-resistant (–40°C), -XB9 low-speed (10 to 50 mm/s), -XC6 stainless steel parts, -XC22 fluororubber seals and -XC85 food-grade grease.

Installation & Maintenance

• Align the rod with the direction of the load. Use a floating joint, clevis or trunnion where the load path is not perfectly straight, so that the rod and bushing are not side-loaded.
• Keep the kinetic energy at the stroke end within the catalogue limit. If the load or speed is too high for the rubber bumper, choose the air cushion or add an external shock absorber.
• Use meter-out speed controllers on both ports for smooth, controllable motion.
• Supply filtered, dry air. The cylinder is pre-lubricated and does not need lubrication. If lubrication is started, it must be continued.
• In dusty sites, such as cement, aggregate and fertiliser plants, consider the rod boot or the heavy-duty scraper option (-XC4) to protect the rod seal.

Typical Applications in Oman & the GCC

The CG1BN40-100 is a general-purpose actuator for pushing, lifting, clamping, diverting and gate operation on packaging, food and beverage, building-materials and general automation equipment. Its round tube and wide range of brackets make it a common choice for retrofit and maintenance work in plants across Oman and the GCC.

Why Source the CG1BN40-100 from Seven Star LLC

Seven Star LLC supplies SMC cylinders, mounting brackets, rod-end accessories, seal kits and auto switches across Oman and the GCC. Send us the code from the nameplate and our team can help confirm the correct ordering code in the current CG1-Z series. Request a quote with your quantities.