Twin-Ram Tilt or Rotary Tilt Coupler?

Which is best?

Twin-Ram vs Rotary Tilt Couplers

Tilt couplers offer a vast array of opportunities to the excavator owner and operator. For many, a tilting coupler is not an option but a necessity. But once the decision to tilt their attachments is finalised, the question soon arises as to what kind?

Twin-Ram Tilt Couplers

Twin Ram tilt couplers use two (twin) hydraulic rams to ‘push’ the attachment to one side or the other. The concept and design are relatively simple and easy to understand. Excavators already possess several hydraulic rams, so the tilt mechanism is merely two more.

Rotary Tilt Couplers

Rotary tilt couplers use a mechanism called a rotary actuator to tilt the attachment. Hydraulic oil is pumped into an enclosed helical chamber, which rotates the inner drum, in turn rotating the bottom section of the coupler. This system is more complicated than using hydraulic rams but has its advantages.

So, which is better?

The answer to which type is best depends on many factors, including primary usage and budget. But before we get to the specifics, let’s take a look at some traditional opinions, the type of comments you’re likely to hear from industry laypeople.

1. Rams are cheaper
2. Rotary actuators are narrower
3. Rotary actuators tilt further
4. Rams are more powerful, with more break force
5. Rotary actuators are more complicated (and less reliable)

Many of the above arguments come down to personal preference and sound like the perennial Ford vs Holden debate. The truth is that the margins between the two systems have shrunk over the years, to the point at which they’re barely perceptible.

1. Twin-ram tilt couplers cost an average of around 25 percent less than rotary couplers. However, when factored against the total investment of the excavator package, price alone should not be the primary purchasing decision.
2. Rotary actuators are significantly narrower than twin ram applications, the latter of which must be in a ‘V’ formation to operate. Rotary tilt couplers, in fact, are no wider than the narrowest of attachments. However, this only becomes a limitation when working in narrow trenches.
3. The design requirements of using twin rams to tilt the coupler result in a maximum rotation of 45 degrees each way (90 degrees total). Rotary tilt couplers can tilt at least 60 degrees (120 total), and mini tilt sizes can rotate up to 90 degrees (180 total). If tilt angles of more than 45 degrees are necessary, the choice is limited to rotary tilt couplers.
4. Rams have a slight advantage over rotary actuators when it comes to break force, but it’s less than ten percent in most cases.
5. Rotary actuators are slightly more complicated in design and construction than a pair of rams, but continued development has resulted in reliability on par with the other format.

There are a few other factors to consider when making a tilt coupler decision, the importance of which will depend on the expected workload of the excavator.

1. Hose routing. Rotary actuators have all hose ports conveniently located on top of the drum, safely between the ears. Twin ram configurations, on the other hand, require hoses to be routed to the tops of the cylinders — outside the protection of the ears. Due to the necessity of allowing sufficient slack in the hoses for full rotation, some twin ram models require hoses to loop outside the coupler, where they are vulnerable to entanglement. The Wedgelock Twin-Ram Tilt Coupler has mitigated this issue by placing the hose mounts on the inside of the cylinders and providing unique routing galleries that allow all supply hoses to remain within the ‘V’ of the coupler.
2. Pressure Relief Valve. Rotary actuators include an in-built pressure relief valve to protect the components from spikes or changes in hydraulic supply. Cylinders do not have this protection – although, to be fair, they are rarely susceptible to damage from over-pressurising.
3. Protection from contaminants. Rotary actuators are an enclosed system protected by robust seals at each end of the rotating drum. Cylinder seals are also pretty bomb-proof, but the ram component is regularly exposed to mud, dust, water and oil. Every time the ram is withdrawn into the cylinder, the seals are expected to wipe it clean of contaminants. It would be fair to say that cylinder seals located at the end of the dipper arm are more vulnerable to eventual damage than those operating, say, the excavator boom. This is a negligible difference, but if you expect your excavator to spend its life up to its elbows in wet clay, the enclosed environment of a rotary tilt might be preferable.
4. Maintenance. The moving components of all couplers should be checked and greased regularly. But it’s probably safe to say that cylinders are slightly more tolerant of misuse (failure to lubricate regularly) than rotary actuators. Another marginal difference – especially for conscientious operators – but something to consider if the machine might go weeks without use or have multiple operators.

The verdict?  

In the end, the decision on which type of tilt mechanism to buy depends on the intended use of the excavator. If high tilt angles or a narrow carriage are necessary, then there’s no decision to be made. Only a rotary actuator will suffice. On the other hand, as the purported ‘advantages’ of twin rams over rotary actuators are minor (including the extra cost when spread over several years of ownership), perhaps the ‘future proof’ decision is to stick with rotary tilt couplers.

That said, the twin ram tilt coupler is a proven workhorse for most applications.

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