4” Cylinder vs. 5” Cylinder for a Log Splitter - What Is the Difference?

When speaking about a log splitter’s hydraulic cylinder, you may hear “4” cylinder” or “5" cylinder." This measurement is referring to the cylinder’s bore (inner diameter).

The bore of a cylinder is notable because it correlates to the cylinder’s rod and stroke, as well as the power and speed of the log splitter the cylinder is equipped with.

So, besides the bore size, what is the difference between a 4” and 5” cylinder?

 

Determining the Cylinder’s Rod and Stroke

Nearly all Timberwolf log splitters have the option of a 4” or 5” cylinder (TW Series not included).

Most of Timberwolf's 4” cylinders have a 3” rod and 26” stroke while all 5” cylinders have a 3.5” rod and 26” stroke. Only TW Series log splitters are constructed with a 4" bore, 3" rod, and 24" stroke.

The measurement of the rod refers to the bore of the rod. The rod itself is what extends from the cylinder to split logs. So, it makes sense that the 5” cylinder has a slightly larger rod diameter than the 4” cylinder.

Photo: interfluid.co.uk

A cylinder’s stroke is the distance covered by the rod and piston between the in and out positions (Blogger, 2020).

Surprising as it may be, small differences in these measurements can completely change the performance of a hydraulic cylinder.

 

Power and Speed

Timberwolf’s 4” cylinder offers ~37,700 pounds (~19 tons) of splitting force while the 5” cylinder offers ~58,905 pounds (~29 tons) of splitting force. Why does the 5” cylinder have so much more power than the 4”?

Simply put, the larger the bore, the more force a cylinder can develop (Matt, 2023).

The force of a hydraulic cylinder is determined by multiplying the cylinder’s PSI (working pressure) by the effective area of the cylinder.

All Timberwolf cylinders - and most others on the log splitter market - have a working pressure of 3,000 PSI.

The effective area of a hydraulic cylinder is determined by calculating the radius of the piston, and then multiplying the piston’s radius by 𝛑. 

For example, the force of Timberwolf’s 5” cylinder can easily be determined:

• 5 (cylinder bore)/2 = 2.5
• 2.5 squared = 6.25 (piston radius)
• 6.25 x 𝛑 = 19.625 (effective area)
• 3,000 (PSI) x 19.625 = 58,875 (force)

Or you can use this simple hydraulic force calculator.

A large cylinder bore also lends itself toward more speed, but a cylinder may be faster or slower depending on the engine equipped to the log splitter.

For example, the Alpha 5 has a 12 HP engine and the Alpha 6 has a 20 HP engine. Both units have the same splitting forces, but the Alpha 6 cycles in 5 seconds with the 4” cylinder and in 7 seconds with the 5”, while the Alpha 5 cycles in 8 seconds with the 4” cylinder and in 10 seconds with the 5” cylinder.

 

Timberwolf’s Cylinder Options

Timberwolf currently has three lines of log splitters, namely the TW Series, HD Series, and Alpha Series. The TW Series consists of the TW-2 and TW-3, which can only be equipped with a 4” bore and 24" stroke cylinder.

All HD and Alpha Series wood splitters can be constructed with a 4” or 5” cylinder.

As a general rule of thumb, opt for a 4” cylinder if you are working with smaller logs and a 5” cylinder for large blocks. There are differently-sized hydraulic cylinders on the market, but larger cylinder bores will offer more force while smaller bores will cycle quicker.

 

References