Robertson Super Comby

On a recent trip to the mainland, Jaiden Drought caught up with Don Robertson and the team at Robertson Manufacturing in Hinds, south of Ashburton, to check out the improved Super Comby EX, which they’ve built over 1000 times and is still flying out the door like hot cakes.

The Comby idea was initiated and designed by Don Robertson in the mid-90s. He essentially turned a conventional silage wagon side-on and ensured it could feed both bales and pit silage. Once this got off the ground, he then tacked another set of floor chains on the back to create the Super Comby, which gave the machine considerably greater flexibility and capacity. The moving rear floor design was patented, and although other designs such as pushes work just as successfully, with the Robertson you can actually move the pusher backwards but you can’t move the load.

It is a common misconception that the Super Comby, or the Super Comby EX for that matter, is a bale feeder. Although it can feed bales, this is only one of its many uses. The Super Comby EX I tested has a heaped capacity of 14.5m3 of grass and maize silage, plus there is the added flexibility of being able to feed five round bales or up to 12 squares through the one machine. Essentially, it’s a side-feed silage wagon and bale feeder all in one machine – it’s all good stuff.

The capacities are increased if you add the rear forks and extension bin onto the rear of the machine, bolstering the heaped capacity to 17m3, but I will touch on that later.

Expanding on the overwhelming success of the Comby and Super Comby, the slightly larger and more refined Super Comby EX now continues the Robertson reputation for reliability and strength that so many farmers have come to love. We have used a Robertson Super Comby on our farm in Taranaki for nine seasons now and have had an exceptional run out of it, so I can personally vouch for the reliability and clever design of these machines. It is fair to say I was interested to see what tweaks had been made from the Super Comby to the EX version and what customers liked about the machine.

Our test machine is owned by the Lovett Brothers, who farm just outside Ashburton on their parent’s farm. The pair is in their first year milking 500 cows, after converting the 240ha beef farm. They looked at a variety of machines and, when it came down to it, they couldn’t go past the Super Comby EX for its heavy-duty construction and versatility. Owning the machine for just over three months now, they couldn’t be happier with its performance, simplicity and ease of use.

The design

The Super Comby EX has three separate sets of chains. These split the load up and relieve pressure on the machine so it is not moving the whole wagon’s contents all at once. Bearing this in mind, the best way to load the machine is in two parts, particularly if using a shear grab. This means the rear floor and the cross feed are essentially two loads that are then fed out in two parts: feed the front section then move the rear floor onto the cross conveyer and feed that out.

The rear floor overhang has been extended in the EX so it is cleanly dropped onto the cross conveyer for clear feeding of the material. Not only is loose feed easily dropped on but a “bale manipulator” is included, which is part of the front of the machine that drops down when the rope is pulled from inside the cab, allowing you to keep bales on the round so they are in the right position for the easiest feeding out. As you move the bale forward, the bale manipulation comes back up and usually locks in by itself, so you can repeat it for the next bale.

The thing I really like is the overall visibility of the machine and the user’s ability to see exactly what’s going on, which is excellent, especially for round bales as they are hard on any machine if they end up in the wrong position when the machine continues to try and rip them apart.

The tilting elevator allows varying of the feed discharge rate, in addition to setting the speed of the chains via the flow rate of the tractor hydraulics.

How does the feeding work? Lower the tilting elevator to the desired height and then pull the other lever to engage the elevator chains. This means that you are in complete control of the feed from the offset; once the hydraulics are engaged the whole load doesn’t start to move. Once the drive is engaged, all other controls are run through the electric joystick. This comes standard with every Super Comby EX and not only makes the machine almost idiot-proof to use, it also allows operators complete control – something which is vital, particularly with bales on board. Two remotes are needed for the standard machine, but if you run the rear forks option, a diverter valve can be used via a switch on the joystick. If the tractor is equipped with three remotes, the choice is yours.

In the past, the downside to these machines was their ability to feed onto a feed pad. A new feature from Robertson is the feed-pad adaptor kit that can be either spec’d on the machine from new, or retrofitted onto existing machines where the elevator comes from underneath the cross conveyer, rather than beside it to gather fine material such as maize silage. This works well, but I still believe (and Robertson agrees) that if you want to feed mainly maize silage or a mixture of high-concentrate feeds on a feed pad, then the Comby range isn’t for you. One of the Robertson side-feed wagons is a better alternative. Although you can feed bales in side-feed wagons, ask anyone who has done a lot of them (particularly rounds) and they will tell you it can be a nightmare that’s guaranteed to end poorly, either on a Sunday or when you have to go somewhere as a promise to the wife. To avoid the stress and sudden disappearance of those all important brownie points, go for the Super Comby EX: two machines in one.

The build strength

The Super Comby EX has been beefed up to handle a slightly larger payload than the original Super Comby, but it functionally remains the same to operate. Some of the refinements include 2″ floor drive shaft, a much heavier walking beam and tandem-axle assembly with 70mm hubs and stubs, as well as running on larger 400/60 x15.5 tyres. The floor slats have also been upgraded, with 50×50 bars on the rear floor and plate welded to the cross conveyer bars to stop any bowing. A more compact drive design on the side of the machine not only allows for the added weight of the extended rear compartment but the grease nipples are also more accessible. All machines are built at the factory in Hinds. Some staff have been there for 20 years or more, so you can’t qualm about the lack of experience on board. Also, to help fight the elements and the harsh conditions the machines are subjected to, every machine is sandblasted and finished with two-pack heavy-duty polyurethane paint.


Although the test machine wasn’t equipped with scales, I just want to mention the system that Robertson runs, as it is not only bloody clever but allows the machine to stay rigid and is the only machine on the market that doesn’t run scales as a double chassis. This reduces the overall weight of the machine and allows the already low overall loading height to remain unchanged.

The Robertson system can be adapted for its normal side-feed silage range, as well as the Comby range. On the EX, it utilises four load cells between the axle and the chassis and a further two on the drawbar. This has been modified to be made up of two pieces, so the cell-mounted section slips inside the drawbar V with a load cell above and below to give the reading.

The other little crafty feature about the front load cell assembly is the drawbar stand also slips though it, so the wagon will weigh the same whether it’s on the hitch or the stand to give greater accuracy.

Side-mounted dispensers

A large, full side-mounted grain/meal feeder can be clipped onto the machine behind the elevator, with a rear shoot so the high-concentrate feed is spread evenly and neatly on top of feed that has just been placed on the ground. This is very popular with high country users, particularly in the winter when the stock’s total daily requirements sometimes need to be fed on top of the snow.

In addition to the grain dispenser, there is a magnesium dispenser with the capacity of 50kg (two bags). This is much smaller and is mounted in front of the wheels directly behind the elevator, so it drops straight onto the feed without creating a dust storm. Both units are hydraulically driven with a small auger to allow the spreading rate to be adjusted.

Rear forks and extension bin

Standard machines come with a rear fine-mesh door, which compactly folds around to the left-hand side of the machine, if you want to load bales in the rear with a separate tractor. For those operators who feed a lot of bales who only want to tie-up one tractor, the Comby series can be spec’d with rear-loading forks like that of the test machine. These can be run though the third remote or as a diverter option on the joystick. For those wanting more capacity, a rear extension bin can be hooked onto the rear forks. These can give another 2.5m3 capacity for very little outlay.


I am a huge fan of these machines; I was before I tested the EX, but having seen some of the design changes to slightly improve the original Super Comby, the machine really is well refined and perfectly suited for a wide range of farming operations. I have used one for nearly 10 years and I personally recommend it – it is a sound investment, one you will not regret.


  • Load dividing takes pressure off the machine
  • Electric joystick control
  • All types of feeds can be fed through one machine
  • Heavy-duty construction
  • Clever design
  • Tilting elevator
  • Bale manipulator
  • Can run scales though single chassis
  • Low loading height
  • Extension bin can increase capacity for little extra outlay


  • Machine width at 2.9m is tricky to get through some gateways, but the width is at the front of the machine which makes this easier to navigate

Photography: Jaiden Drought

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