Tree stump grinders come in all different sizes from handheld chainsaw attachments, which are ideal for getting too restricted areas. Pedestrian machines, that come in various sizes from approximately 7 hp to 30 hp. Then there are radio remote for wheeled machines and tracked machines for the professional.
Tree stump grinders can also be fitted to their three-point linkage on an agricultural tractor, which is great if you have space, these are not normally suited to garden projects. There are also tree stump grinder attachments that can be mounted to a digger.
And finally, there is the auger type that can literally drill out your tree stump. These machines are ideal if your tree stump is on a bank and out of reach for a conventional machine.
I’ve just been looking at the Stump Crusher 850 Pro by Dipperfox. I came across this machine by accident through communicating on LinkedIn, it’s amazing what you can find on LinkedIn! Apparently, the Stump Crusher 850 Pro By Dipperfox is made in Estonia, the first prototype model was built in 2018.
I really like the principle of this machine, it’s certainly a very different way of removing a tree stump. Traditionally, stump grinders have a cutting wheel that spins at high speed, with a number of teeth that chip away at the tree stump and grinds well below ground level, it’s a good way of removing tree stumps. The stump crusher 850 pro takes more of a drilling action rather than a cutting action, I like this principle, especially for clearance jobs. The downside is that the stump crusher 850 pro takes a lot of hydraulic power.
The manufacturer recommends a minimum of a 100 hp excavator, so you are talking about 20 ton plus machines, not something that can easily be used in the average garden! It would be great if Dipperfox could perhaps make a smaller machine that would fit on smaller excavators, maybe this is easier said than done due to the hydraulic oil flow required.
180 stumps in one hour – the fastest and quickest way to remove a tree stump.
Heavy-duty bolt on steel blades.
Ideal for forest situations and some urban areas.
Easy plug and play instalment.
Heavy duty gearbox.
Wait 575 kg.
Power requirement minimum of 100 hp
Weight 14 to 30 tons
Simple Cutting Principle
The Stump Crusher 850 Pro By Dipperfox has more of a drilling principle rather than a high-speed traditional stump grinding cutter head. I like the idea of this principle as there is no flying debris, it’s much quicker than traditionally grinding a tree stump and the work rate is excellent. In a forest situation, the pieces of wood would quickly rot down, it may be slightly different in a residential area. Whether the slices of wood can be cut smaller by drilling a second hole, I would guess the remaining debris could be made smaller with a second pass of the stump crusher.
The two cutting blades look extremely heavy duty, it would be interesting to know how often the blades need changing. My guess would be that it would be fairly frequently considering the excellent work rate of the stump crusher. The auger type drill bit would also take a fair bit of wear and tear, I guess, I would really like to see one of these machines in action, maybe I will one day soon.
Here is my review of the Predator 38 RX EFI radio remote stump grinder.
I have been using Predator stump grinders for the past four years, prior to this I was using American Carlton stump grinders. One of the biggest reasons for changing to a Predator 38 stump grinder was the fact that the Predator has the ability to be able to fit through narrow gateways. This is a huge benefit for small English gardens!
My first Predator was a Predator 28 RX radio remote diesel machine which had its fair share of problems. I then went to using a petrol carburettor (Predator 38 RX) machine for a short period which worked absolutely fine, although quite heavy on fuel. I now have a Predator 38 RX EFI radio remote stump grinder which is so far going really well.
At the time of creating the video I had about 200 hours on the clock, I now have about 270 hours which has been trouble-free. This is after approximately six months of use.
You Can See My Video Review Of The Predator 38 RX EFI Radio Remote Stump Grinder Below
Narrow Stump Grinder
One of the best features about the Predator 38 RX EFI is the fact that it is as far as I know the narrowest machine on the market in its class. The Predator narrows down to just 26 inches (66 cm) which means it will fit through most garden gates. I believe the next machine up is about 3 inches wider in size, which is not a huge amount. However, I know that I am often up to my limits when it comes to getting through narrow gates, this is something that the Predator 38 EFI does well.
Just one thing regarding narrowing the tracks; bringing the tracks in is purely for getting in narrow gateways. Great care needs to be taken when manoeuvring machine as it is very unstable when the tracks are at the narrowest point. This is fine for going to gateways, just take care as any small divot’s in the ground can quickly make the machine catch a gatepost or other obstacle.
As I mentioned at the start of the post, I used Carlton American stump grinders for many years, they are well-built machines, however, it’s that width problem again! My Carlton 4012 stump grinder had dual wheels which could be removed for narrow access jobs, this helped, however, it was a fairly painful exercise and time-consuming. It is far easier to flick a switch on the radio remote and watch the tracks narrow up.
Kohler 38 EFI Engine
I never expected to be purchasing a petrol stump grinder, however, I have and I’m very pleased with the result.
To be fair, I would prefer to have a diesel engine stump grinder. But after having so many problems with the Lombardini engine on my first Predator. I decided to go with the petrol engine version. I was using a petrol carburettor engine model for a few months which worked absolutely fine, although it was quite heavy on fuel.
The Kohler EFI petrol engine is a great improvement on the carburettor model. Although they are almost the same engine the EFI makes a huge difference not only in the economy but also low down torque. The carburettor was a bit slow when you need more fuel, however, the EFI engine reacts almost instantly. Definitely a great improvement over the carburettor Kohler engine.
The Kohler engine also offers more power than the diesel version. The Kohler EFI engine develops 38 hp whereas the Lombardini diesel engine develops 28 hp. To be fair the actual performance of the Lombardini engine on my previous machine was absolutely fine. However, reliability was not! I do not hear many good things about Lombardini engines.
Multi-Tip Cutting Wheel
The Predator 38 EFI comes with a multi-tip cutting wheel complete with six teeth. Only two of the teeth actually carry out the cutting, the other four teeth are for clearance. Normally, I only replace the two cutting teeth regularly. For the other, for clearance teeth, I normally replace these as and when they are worn with used cutting teeth.
After trying finger teeth and green teeth on previous machines, I do prefer the Multi-Tip cutting system. Finger teeth were continually breaking on a daily basis, it’s not a five minute job replacing finger teeth!
Would I Recommend The Predator 38 RX EFI?
Yes, I definitely would recommend the Predator 38 RX EFI. I would avoid the diesel models as my experience has not been good. The greatest plus point of the Predator stump grinder is being able to get into gardens with limited access. The grinding capacity is also excellent.
One thing I would like to see is a slightly better build quality. On the other hand, I guess the manufacturer is trying to keep the weight to a minimum. I believe this is one of the reasons I had so many problems as my diesel Predator stump grinder suffered from vibration issues.
Overall, if you’re looking for a stump grinder with a good capacity for work, I would go for a Predator 38 RX EFI radio remote stump grinder.
Multi-Tip or green teeth stump grinder cutting wheel? What is your experience, I would like to find out more?
I have owned and used several different Predator stump grinders, my current Predator being a petrol radio remote Predator 38 RX, which I’m more than happy with.
My Predator is fitted with a Multi-Tip cutting wheel which in general I really like. Over the years I have used traditional finger teeth and also green teeth, the cutting efficiency is very good on the Multi-Tip wheel. Another great advantage of the Multi-Tip cutting wheel is the fact that the teeth are extremely quick to change. I guess it takes about 3 to 4 minutes to change the two lead cutting teeth.
There are six identical teeth on the cutting wheel, but only two teeth actually cut, the other four teeth are just for clearance. The teeth work in opposite pairs so there are actually three different positions on the cutting well, obviously, the forward-positioned teeth are the cutting teeth.
However, one problem that I have continually encountered is bolts shearing off, which is annoying and time-consuming. On average, I would say I lose 30 minutes each time a bolt shears off. Now I know I said a couple of paragraphs back that it takes 3 to 4 minutes to change to teeth. However, when a bolt shears off, you need to find the keeper block, the tooth and remove the broken bolt from the threaded insert, this takes time. Plus you need to go and find your tools to replace the bolt.
You Can See My Video On The Multi-Tip Cutting Wheel Below
With my present stump grinder, it had carried out about 15 hours work when the first bolt sheared. Once the first bolt shears, many more broken bolts will follow! I can actually have days where I shear 3 to 4 bolts or none at all!
My question is; would I be better off with a green tooth cutting wheel. In the past I tried using the green teeth cutting system on a Carlton machine, however, the pockets almost wore faster and the teeth! This became an expensive process due to the fact I was and regularly replace the pockets. I believe that this could be rectified by using larger green teeth.
I believe that one of the biggest problems is with the Multi-Tip cutting wheel is that the wheel is not hard enough. Predator gave me a new Multi-Tip wheel a few years back due to the fact they had some wheels that were not hardened correctly.
I would be interested to hear what your experience is on the Multi-Tip cutting wheel and your experience of using green teeth?
Review Of The Predator 28 And 38 Radio Remote Stump Grinder
Here is my review of the Predator 28 and 38 radio remote stump grinder. This is a review of the Predator stump grinder that I own and have personal experience with, having operated for many hours! I have created a video review of the two Predator stump grinders below.
I haven’t created this review to be negative, it’s just a genuine review of the Predator 28 and 38 radio remote stump grinder. I would be very interested in hearing about other people’s experience, good and bad.
First of all, I would like to give a positive review for the Predator 38 stump grinder, I have had the Predator 38 tree stump grinder on hire from Ben Burgess several times and have probably clocked up around a hundred hours of use with this machine. I believe that the Predator 38 and 28 stump grinders are the narrowest machines in their class on the market, both narrow down to 26 inches (66 cm) which is fantastic, if you have used the traditional pedestrian stump grinders you will understand why it is so useful to get through narrow gateways and not have to struggle with a pedestrian machine.
I would also like to mention that I have been looked after extremely well by Ben Burgess, who are Predator dealers if you’re looking to buy or hire a stump grinder I would definitely recommend Ben Burgess. Or if you’re looking for a second-hand stump grinder it may be well worth checking out eBay.
You Can See My Video Review below
Predator 28 Radio Remote Stump Grinder
I purchased my Predator 28 radio remote machine in October 2016, I have to say I have had my fair share of problems which I will talk about more in this review post. In the three years of owning my Predator, I have probably called them 150 to 200 times in under three years. Over the past 30 months, I have had approximately 40 breakdowns that have stopped me working! It is good to point out that the Predator 38 has given me absolutely no problems at all and in my experience, it’s a good machine to purchase. The biggest plus point is that the Predator 38 has a fair amount of power for a machine of this size and can cope with any sized tree stump.
On the downside, it does use a lot of petrol, if you’re using the Predator 38 continually for a day it will use around £100 worth of fuel, on my Predator 28 diesel machine I will probably use about £30 worth of red diesel. However, probably on an average day, I will use around £35 worth of fuel with the petrol machine. You can see another post I wrote about the fuel consumption of the Predator 38 here.
I purchased my Predator 28 radio remote diesel stump grinder back in October 2016, prior to this I had been using a Carlton Lombardini diesel radio remote 4012 machine and also a petrol SP2000 pedestrian machine.
The biggest reason for me purchasing the Predator 28 was due to the compactness of the machine, which has proved to be a very useful feature time and time again.
I went for the radio remote machine with a Lombardini diesel engine, the machine that Predator demonstrated to me was a manual machine which I had no intention of buying, but it was the only one they had available for a demonstration. If you are buying a stump grinder and there is a radio remote option, I would definitely go for it, it is so much easier to use and saves a lot of time.
I hadn’t carried out many hours work when probably at around 10 hours work the jubilee clip that assists holding the baffles on the exhaust broke, I did kind of expect this to happen as jubilee clips are certainly not strong enough for holding anything like an exhaust in place. Also, in my experience of Lombardini engines, it’s very rare to see them with the exhaust in the right place after they have been used on a stump grinder. I have experienced this with my Carlton machine and the Predator.
After the jubilee clips broke that was quickly followed by the baffle plate vibrating loose and literally tearing the metal on the exhaust. I understand that it is much better not to have anything attached to the exhaust whatsoever otherwise this only causes issues. I believe I am on my fourth exhaust and will be on my fifth exhaust in about a weeks time.
Have you experienced problems with your Lombardini exhaust lasting? I have certainly had issues over the years with keeping an exhaust in one-piece!
Multi-Tip Cutting Wheel
The Predator comes with Predators own multi-tip cutting wheel, the wheel consists of six teeth, two of which carry out the main grinding and the other four are clearance teeth. All the teeth are identical and changing the teeth is exceptionally simple, just one bolt to hold the teeth in place, the teeth can literally be changed in a few minutes.
In my experience, I’m really pleased with the performance and the ease of changing teeth. I’ve used the old-fashioned finger teeth which are very time consuming to change and break regularly in my experience and I have also tried green teeth, without much success.
Unfortunately, after about 30 hours of work, I started to break lots of bolts that hold the teeth in place, on average I was breaking three per day. I purchased a new multi-tip cutting wheel which again solved the problem, however, after 30 hours the problems started again. Predator did tell me that they had had a few issues with some soft metal wheels that had not been hardened properly. In fairness to Predator, they gave me a new cutting wheel free of charge. The only problem being that because I was breaking so many bolts, it wasn’t always possible to find the teeth and the blocks that hold the teeth in, which obviously incurs more cost in replacing them.
Apart from this issue, the multi-tip cutting system has been the best cutting system that I have used.
What is your experience with stump grinder cutting wheels and which system do you prefer?
Incidentally, I have just had the main cutter head bearing replaced after approximately 800+ hours which I reckon is pretty good as the cutter head takes a beating in the best possible way. I always give one or two pumps of grease before carrying out a days work. Apparently, on this machine, you can over grease and push the seals out if you’re not careful, hence the one or two pumps of grease.
Belts To The Cutter Head
The belts to the cutter head are something that in my experience need quite a bit of attention, I fully understand and appreciate that these belts are under considerable load most of the time. Obviously, new belts stretch, so after around six or seven hours it is important to tighten up the belts.
This is a reasonably straightforward process, originally I used to take the five bolts that hold the rubber guard off but now I have cut through the rubber guard, so I simply have to take the metal belt guard off to access the cutter head belts.
To tighten the belts release the four bolts that hold the cutter head on and then undo the nut that releases the cam to tighten the belts. The process can be a little bit awkward when you first carry it out, but it does get easier once you have done the process a few times. The adjuster is a square-headed bolt, I actually have a socket that fits this on a large lever that makes the job much easier.
I’ve actually had the three cutter head belts last up to 300 hours on the other end of the scale I have had the belts last three hours, I have no idea why, but this has happened, unfortunately. I also find that I am tightening these belts a bit more often than I would actually like to, I’m not sure if this is due to vibration from the diesel engine as when I had the petrol machine on hire I didn’t have to make any adjustments at all.
One of the issues that I’ve had with the cutter head adjustment is a spacer/bolt that seems to break regularly, it is a known problem.
As the video shows, I have actually had my bolts changed around as the threads were getting a bit worn, to my mind the new way is much better.
The Electric Clutch
Both the predator 28 stump grinder and 38 have an electric clutch to engage the cutter head, I always engage the cutter head on tick over as I don’t like to see the cutter head snatching in as I feel this shortens the life of the electric clutch. However, unfortunately on the petrol machine, you have to have a few revs to engage the clutch, otherwise, the machine will simply stall. I am told that with the new petrol model with the Kohler EFI engine you can engage the electric clutch on tick over which is great news.
I have had no issues with the electric clutch so far.
Predator 28 Stump Grinder Engine Drive Belts
In general, the engine Drive belts have lasted quite well, there are three belts from the engine then go onto a pulley system and then three more belts that go to the cutter head.
Unfortunately, my first Predator 28 stump grinder engine Drive belts broke at 19 hours, however, the next set of three belts lasted well over 500 hours and the present set of belts have done about 300 hours of work.
To adjust these belts is very straightforward, simply loosen four large bolts on the base of the machine and to the rear of the machine, there is a thread where you simply turn the bolt to tighten the belts, very straightforward indeed.
Lombardini Diesel Engine Issues
I’m afraid my experience with Lombardini diesel engines hasn’t been brilliant! On my Carlton stump grinder, which was powered by the same Lombardini engine, the crankcase casting cracked. It was only a hairline crack but it was replaced under warranty as apparently, Lombardini had a batch of castings that were faulty.
I also owned a Lombardini diesel engine on a BCS rotavator, believe it or not, this engine was fine, however, the machine was stolen so I never found out if the engine was long-lasting or not or even trouble-free!
First Lombardini Engine
Anyway back to my present Predator 28 stump grinder, after just 30 hours the engine failed to start, apparently, this was due to the engine sucking in some soundproofing material that was on the flywheel cover. I did notice when the machine was delivered that this material was loose, however, I didn’t take much notice as I knew it had all been pre-checked.
When the engine was checked by the local Lombardini agent, they discovered that the machine had sucked in the soundproofing and the engine had overheated, this engine was replaced under warranty.
Second Lombardini Engine
My second Lombardini engine managed about 650 hours on the Predator 28 stump grinder, obviously, I checked the oil regularly and I suddenly noticed that the engine had used more oil than normal. In general, the engine burns very little oil, I probably add a small amount about every six weeks in normal conditions. The recommended time for changing the oil is 200 hours but I tried to change the oil at 100 hours as I feel it’s better to change the oil regularly rather than wear metal!
When my local Lombardini dealer stripped the engine down they discovered that dirt had entered into the engine, I don’t quite understand this as I’m always extremely careful with maintenance. The engine has a oil bowl filter which I am told is the best for dusty conditions. There’s also a clear Dyson type prefilter which removes most of the dirt and dust, which then goes through to the oil bowl and then through to a mesh filter and finally a spongelike filter before the air finally reaches the engine. I would expect with all these cleaning processes for the air to be clean.
I will clean the prefilter two or three times a day, depending on conditions and I will also change the oil in the oil bath filter halfway through the day if the conditions are poor.
However, despite this maintenance, I had to replace the engine at cost to myself! I see many tree surgeons who rarely clean their air filters out and yet they don’t seem to have had the problems that I have had!
Third Lombardini Engine
After being unbelievable careful with this new Lombardini engine after just 160 hours the exact problem had started again. I checked the oil and on one particular occasion, I noticed that the engine had used more oil than it should have done! So now we are back to square one and another new engine is coming!
Fourth Lombardini Engine Coming
The engineers removed the air filter in front of me and to me, the air manifold looked clean, however, they did say that small amount of dirt had got through the filter and into the engine!
To me, the air filter is not doing the job if dirt is getting through. I have genuinely been cleaning the filter daily and more as I mentioned previously.
Just the other day I was speaking to a tree surgeon about the issue and he mentioned that he had a problem with his Timberwolf chipper in the morning. Apparently, it was blowing out black smoke and not revving properly. He checked the air filter and he said is absolutely blocked solid and once he cleaned the air filter the engine ran perfectly. I asked him how often he checked the air filter and he said he only checks it when there is a problem!
It really doesn’t make sense why these engines are wearing out so rapidly, especially as I am an owner-operator and take care to keep the engine clean.
What has been your experience with Lombardini engines on your Predator or any other stump grinder come to that?
Hydraulic Cooling Fan On Predator 28 Stump Grinder
The Predator radio remote stump grinders have an electric cooling fan to cool the hydraulics, this is due to the oil getting warmer with the radio remote stump grinders.
I am now on my fourth fan and so far this latest fan has lasted me several hours, fortunately, Predator has replaced these cooling fans free of charge. I believe that the issue with the fan is probably more due to the vibration of the diesel engine.
What’s your experience with the hydraulic cooling fan on your Predator?
The Fuel Pipe Burst
After about 40 hours of use the rubber fuel pipe burst, spraying diesel everywhere. I had to call the local engineers out to replace the rubber fuel pipe. On inspection of the old fuel pipe, it didn’t look like it was up to standard, thankfully the issue hasn’t happened anymore!
Hydraulic Oil Leaks
Ever since I have had my Predator there has been a hydraulic oil leak from the main hydraulic oil tank. I appreciate on top of the oil tank there is a breather and the system has to discharge a small amount of oil, however, this is more like a river of oil!
There have been attempts to fix this issue, but so far with no success! Obviously with oil leaking and then running onto the tracks can be an issue with people’s driveways, so there is a constant mopping process going on!
Have you had hydraulic oil leaks on your Predator?
Five Batteries In Three Years
It seems that my Predator 28 seems to get through a terrific amount of batteries!
The first battery went after about 60 hours, I called Predator to see if they could help, they talked me through a few checks over the phone which seem to point to the battery being the problem.
The RAC Came Out
it appeared that Predator were unable to come out to my breakdown, in fact, they have never been able to come out to a breakdown, so I decided to call the RAC!
The RAC came out and were slightly surprised that they were going to look at a stump grinder rather than a motor vehicle! However, the engineer was extremely helpful and carried out all the necessary tests that proved that the battery had failed. He was able to fit me and you battery but he did mention that it would not last due to the fact that the Predator battery is of a special specification for this machine due to the vibration. He was right, the battery lasted 48 hours!
I then purchased a third battery, I guess this lasted about a year before finally exploding on the golf course where I was working, this had to be seen to be believed!
I have never seen a battery explode before, however, after stopping the machine for about five minutes and turning the key to start the machine, aside literally blew out the battery! Thankfully this battery was replaced under warranty by Bosch.
The second Bosch battery stopped working for no apparent reason, so I’m now on the fifth battery that I had to pay for.
How has your battery been on your Predator?
Spool Valve Leak
I recently had to have the whole spool valve assembly resealed as it was leaking quite badly, it had been weeping for some time and then became considerably worse. Thankfully this issue is all fixed now.
Have you had any hydraulic leaks on your Predator stump grinder?
I have also had several charging issues which is down to the Lombardini engine, I literally used to put the battery on charge permanently when I wasn’t using it rather than risking a breakdown. I had the engine checked several times and although it did have a replacement alternator or charging system replaced, it would definitely let me down if I didn’t charge the battery daily.
I would definitely recommend paying the extra for the radio remote controls, it is so much easier and so much quicker to use than the manual machine.
As I mentioned earlier I have used the predator 38 stump grinder for approximately 100 hours and the radio remote has not failed me once.
Unfortunately, with my Predator 28 sometimes the radio remote can work faultlessly and although I don’t understand much about radio signals, I can appreciate that occasionally some interference is acceptable. However, sometimes my machine can cut out 40 times per day, once the radio remote cuts out the machine will stop, then you have to go through the starting procedure again.
I normally find that when the remote signal goes it will happen several times in a row and then just write itself on its own.
Due to the fact that the radio remote is losing its signal so often, I have overridden the sensor on the rear door. So that if I lose the signal the engine still keeps running, this saves a lot of messing around. This stops the engine shutting off at full revs, which I don’t like happening.
Once again, the predator 38 stump grinder didn’t fail me once with the radio remote!
How has your experience been with your Predator radio remote?
I believe that many of the issues that I have had to deal with unfortunately come from having a diesel engine which brings vibration issues. After using the Predator 38 petrol machine I can see that the vibration is considerably less than the diesel machine.
As you can see in the photograph some of the guards have suffered from metal fatigue. Once again I am sure this is from excessive vibration from the diesel engine.
I feel that I have been quite unfortunate with my Predator 28 machine. It seems like I may have had a Friday afternoon machine. I also believe that the diesel engine has created a lot of vibration issues.
If I was purchasing now I would definitely go for the petrol machine as it has extra power, much less vibration. The diesel model and is much quieter which is actually really nice if you’re doing a days work!
As I mentioned earlier, the predator 38 radio remote petrol machine is a great all-round machine. Especially for getting into those narrow gateways that we so often come up against in the UK. If you are looking for a stump grinder the petrol model could be a good option for you. I will definitely be looking at one.
It would be great to hear about your experience with your Predator machine. Or come to that, any other make of stump grinder that you are using. Maybe you could write a review of the Predator 28 and 38 radio remote stump grinder?
Thank you for reading and please feel free to comment below.
I’ve been using a Predator P28 diesel radio remote tracked stump grinder for the past 30 months, my previous stump grinders were a Carlton 4012 radio remote and a Carlton SP2000 pedestrian stump grinder. The P28 stump grinder comes with a Lombardini 28 hp two-cylinder diesel engine, I have had this particular engine on a few machines that I have owned. It’s quite a basic engine and a fairly old design I believe, however, it does seem to be reasonably economical.
Predator also produces a petrol version of this machine with a 38 hp engine. I’m not particularly keen on having large petrol engines on machines like stump grinders as the engines tend to work reasonably hard and I know from owning a Carlton 27 hp petrol stump grinder how much fuel they can potentially use.
I recently had the opportunity to try a Predator 38 hp petrol stump grinder, I have often tried to find out how much fuel the Predator petrol stump grinder would use a day, but I have to say I never really received a clear answer, which suggests to me that they would consume a lot of fuel and with an engine of this size I wasn’t expecting very good fuel efficiency! The answer normally came out that the petrol version uses more fuel but the work rate is much greater than the diesel version.
I Tried The Predator 38
I have to say I was looking forward to trying out the predator 38 stump grinder, with approximately 25% more horsepower I was expecting a very good work rate. I think probably one of the greatest features of the petrol version is the quietness of the engine. The version that I tried had the older Kohler engine which you have to choke almost every time to start the engine, even if the engine is warm, this was exactly the same with my Carlton Kohler petrol stump grinder, I’m not quite sure why they require so much choke all the time? Apparently, the latest petrol Predator stump grinders have the 38 hp EFI engine which has no choke which I am sure is much better for starting.
One of things that I always try to take care with, is to engage the cutter wheel on tick over, the diesel engine is able to do this with no problem, however, the petrol engine requires quite a few revs, otherwise, it just seems to stall the engine. I’m not particularly keen on revving an engine up and then letting the clutch snatch in, I believe it could add to problems later on in the machines life.
Performance And Fuel Efficiency
I didn’t notice any difference in power with the petrol stump grinder if I had not known the petrol engine was 38 hp against 28 hp I would have guessed the engines were similar sizes. It would have been interesting seeing the two machines working side-by-side, however, this is just my personal experience. You see a video of my diesel stump grinder working here.
I tried the petrol predator stump grinder on some Poplar tree stumps, these are not the easiest tree stumps to grind. I was quite surprised when the machine stopped after only one hour and twenty minutes, a tankful of diesel normally lasts me three hours continuous grinding before I need to refuel! I actually only used the Predator 38 for one day as I felt it was much cheaper to use my diesel machine.
I estimate to use around 5 L of diesel per hour which works out to around £30 for a day’s work (approximately eight hours continuous use) using red diesel at 75p per litre. If I was using the Predator 38 all day my estimation would be 100 L of diesel which would cost around £100, in other words, four jerry cans per day!
All The Machines Seem To Be Petrol
It appears that most of the smaller stump grinders and chippers are being powered by petrol engines, due to the emission laws. Personally, I think the emission laws are way over the top and although I agree it’s great to have clean engines, we also have to be practical.
With people moving over to petrol vehicles and machines, it does make me wonder if this is a government incentive to collect more tax. There is a huge difference between £30 and £100 worth of fuel per day!
What are your thoughts on the economics of petrol engines?
Do you think the government is just trying to collect more tax from us by burning more petrol?