With the government change of legislation on red (untaxed) diesel, questions are being raised as to which type of power pack to buy. The two main engines available in the UK market are a twin-engine option or a single-engine - also known as a hydrostatic. There is a lot of information on both types, making it confusing to decide which option to go with. Each engine type has its advantages and disadvantages and it is up to the user to decide which product is best suited to their specific application.

Bucher Municipal supplies twin-engine, electric, and single (hydrostatic) engine-powered sweepers, as do many other UK sweeper distributors. Each driveline type has its advantages and disadvantages while each power type has a different configuration to provide optimum performance to match. With over 100 years of experience, Bucher Municipal sweepers have been improving the design of the truck-mounted sweepers year after year.

Understanding the advantages and disadvantages of each power pack and drive system is key to deciding which one is best suited for your specific applications.

Environment

It has never been more important to focus on the environment. Greener measures are being implemented by all corners of the sweeping industry. Therefore, it is a significant consideration when choosing the engine type for you.

One way to reduce the carbon footprint is to reduce fuel usage. Not only is reduced fuel consumption better from an environmental point of view, but it is also better when considering operational and whole life costs. With the new change to red diesel, knowing how much fuel each engine consumes is a huge factor when budgeting.

Due to the variation in the power types of each drive system, lower fuel consumption is achieved at differing fan and engine speeds for each engine type.

For a twin-engine, the best fuel consumption is at low revs. Lower revs are most common when sweeping as the optimum sweep speed is 5mph. This low fuel consumption is because both engines share the workload; the chassis engine can idle while the secondary (donkey) engine controls all the power for sweeping. With a single-engine, when put to work, the revs are ramped up to maximum in order to both sweep and drive, which burns through a significantly more amount of fuel.

On the other hand, the best performance for a single-engine is at high revs. This is because if both engines on a twin were at maximum revs, that’s double the fuel consumption compared to one and a lot of the power generated is left unused. This rarely happens on a twin-engine however as the shared workload reduces the strain on each engine leading to reduced fuel consumption and reduced wear on parts (lower cost of ownership).

These fuel savings not only benefit the environment but can save you a lot of money in the long run, especially with the change in legislation on red diesel. Additionally, in Europe where they have not ever had a subsidy or equivalent ‘red diesel’ option, municipals and clients still choose twin-engine solutions at a ratio of approx. 10:1.

On another note, although twin-engine sweepers operate at lower revs, there are still two engines, meaning they create more soot in the environment and therefore more particulate matter. This particular matter (2.5 & 10 microns) is harmful to the health of those surrounding the engine. In comparison, single engines do produce lower hydrocarbons and NOx gases for this very point - they only produce as many emissions as the single-engine used. However, this isn’t necessarily an issue, mainly due to the nature of a road sweeper; they are one of the only machines on the road that clean up more dangerous and harmful air pollution than they produce. This factor alone means that fuel consumption is a much larger factor to consider when evaluating the environmental impact of the number of particulates produced.

Performance

When considering the applications and performance of your sweeper there are a few factors to keep in mind. Where will the sweeper be used? How much suction power is needed? How easy it is to operate? These questions are integral in the decision of engine choice.

Twin-engine sweepers outperform hydrostatic when used in heavy sweeping applications such as construction work. They will be able to pick up heavy debris such as road bricks with little effort, due to the power available from both engines working simultaneously. Each engine is dedicated to a separate specific function, with the donkey engine solely focused on sweeping to achieve maximum power and performance.

With a hydrostatic drive, the power available from the single-engine is not enough for heavy-duty sweeping. It is however good for smaller municipal applications. The infinitely variable speed control available from this type of engine is designed for environments that need differing sweep speeds.

Another factor to keep in mind is the introduction of the Bucher patented smooth flow system. This revolutionary technology has a massive increase in suction (+40%) compared to other systems. The increase in power on both engine types broadens the horizon of possibility for both the twin and the single-engine market.

Usability for the operator must be taken into account when deciding which engine is best for you. One of the greatest downsides of a hydrostatic drive is the gear system. In order to move between transit and sweep modes, a single-engine machine must come to a complete stop before the operator can change the intended use. This can be dangerous in busy environments as finding somewhere to pull over and come to a complete standstill can impede traffic, becoming an obstruction. A twin-engine sweeper, however, can effortlessly switch from sweeping mode to transit mode. Once the operator is finished with sweeping, they can proceed to transit mode without having to stop or pull over, improving safety.

Maintenance

Engine maintenance is expensive and frequent repairs and replacements can add up very quickly. This means it should be a big factor in the budgeting and overall decision-making when purchasing a road sweeper.

Twin engines surprisingly have fewer maintenance costs compared to single-engine. There is a number of reasons for this. Because of the shared workload, less pressure is put on each individual engine, the revs for each are much lower so the need for replacement parts and maintenance is greatly reduced. The clutch on a twin-engine is also put under less pressure compared to single engines. Due to the revs on a single-engine being that much higher, replacements are needed more frequently due to the clutch and engine being under a lot of pressure, trying to run both the chassis and the sweeping functions. The cost of replacements and services for single-engine machines can add up quickly when they are not correctly matched to the application as they require specialized, hydrostatically trained engineers.

The issues of having a single-engine also become apparent in the event of a breakdown. If a problem arises with the sweeping side of the machine, the whole unit cannot be moved, leading to a costly and complicated recovery situation. This also becomes a potential safety risk for traffic obstructions and the operator. However, with twin-engine units, because the jobs are split between the engines from driving to sweeping, if an issue occurs with the sweeper function, the chassis engine is still functional and can drive off safely without a recovery being needed.

In reality, there is no definitive answer as to which engine type is best. Both engine types aren’t without their faults and benefits. The applications they will be used for should play a large part in any decision-making criteria and should be studied closely.

If you have any questions our professional and knowledgeable sales teams can support you with your understanding of the options. The advantages these engines have are dependent on application and user preference; municipal sweeping can, more often than not be completed with a hydrostatic drive whereas heavy-duty construction sweeping is almost always completed by a twin - but unfortunately this isn’t always the case. For flexibility or a hybrid solution, twin engines should be seriously considered.

We offer to fit both engine types in our sweepers so whichever engine you feel you are leaning towards can be catered for.

If you have any questions on which Bucher Municipal engine would best suit your application, don’t hesitate to contact our friendly team.