MAZ-5551
Virtually since the beginning of mass production of MAZ-5551 in 1985 and to this day, this car is in almost every village in Russia and other republics of the former Soviet Union. MAZ-5551 compact (for a payload of 8-10 tons) maneuverable and inexpensive car has been extremely widespread, and especially as a dump truck. Read more about the features of the design and specific use of MAZ-5551-compact further.
Intended purpose
MAZ-5551-A maneuverable muldovoz truck, which is designed for transportation of various loose goods. The most often the machine is used to transport construction materials for the construction of buildings and structures. The machine has proven itself perfectly on intraregional routes for transportation of crops and other agricultural loads in the streets. Ten-ton truck is often used for urban areas alignment. Thanks to the heated body in any season, the vehicle can be used for asphalt wear and tear during road construction and repair. Versatility and versatility of the truck also causes its use in various industries.
Technical Specifications
MAZ-5551-A dump truck with double tires 2×4 and double rear tires. The body is a metal body with automatic opening and closing of the tailgate. The rear part is the rear of the tipper trough in the basic configuration. The engine is located longitudinally, under the compacted cab. All power components are mounted on a metal frame.
engine
The most widespread on modern MAZ trucks are four-stroke engines YAMZ-6563.10-03 of Yaroslavl manufacture.
- Type – with compression ignition and direct fuel injection;
- Working volume – 11.15 liters;
- Number and arrangement of cylinders – 6, V-shaped;
- Compression Ratio – 17,5;
- Power – 230 hp (169 kW);
- Maximum torque at 1100-1300 rpm-90 Nm;
- Minimum specific fuel consumption – 200 g/kWh;
- Turbocharging system consists of intercooling of charge air. Air-to-air heat exchanger.
The engines are equipped with fuel supply system by “Yazda” with fuel injection system of “KFT-40” type. The engine meets Euro-3 environmental standards.
Fuel consumption
Fuel consumption of MAZ-5551 is 22 l/100 km. Given the large capacity of the fuel tank (200 liters) the truck can cover over 800 km without refueling.
chassis
Front suspension consists of two semi-elliptic leaf springs with double-acting hydraulic shock absorbers. Rear suspension on two main and two auxiliary springs with a kickstand. Brakes are drum type. The main braking system is pneumatic, for the front and rear wheels separately. Parking brake – on rear wheels with pneumatic actuator, from spring accumulators. Tires – 12.00R20 mod. ID-304.
power transmission
In the basic version, the vehicle is equipped with a five-speed manual transmission YAMZ-236P. Synchronizers are installed on the 2nd, 3rd, 4th and 5th gears. The torque is transmitted from the engine to the elements of the transmission through a double-disc friction clutch. Clutch drive is hydraulic with pneumatic booster. Rear axle is two-stage and consists of central gearbox and wheel reduction gears. Gear ratio of the drive axle is 7.79. Open driveline with needle bearing joints.
Adjustable clutch
MAZ-5551 is equipped with a double friction clutch, traditionally used on heavy trucks. Elements of this unit are subject to wear due to significant overloads in operation and require periodic maintenance.
For example, adjustment of the MAZ-5551 clutch is required in the following cases:
- slipping of the clutch at high speeds
- grinding when shifting gears
- clutch does not fully disengage
There are three main steps:
1. Adjust the 1 mm clearance between the set screws and the center drive pulley as follows:
- Remove the hatch covers to open the clutch and flywheel.
- With the clutch engaged, move the shift lever into neutral,
- Unscrew the locknuts and screw all the adjustment bolts into the center drive pulley as far as they will go, this requires you to turn the flywheel,
- Loosen the bolts one turn and tighten the locknuts with some force.
This adjustment gives the required clearance between the discs and the friction surface of the flywheel. 2.
Leave a gap of 3.3 . 3.7 mm between the nut and the rear valve cover. To adjust, loosen the jam nut and adjust the gap to the desired value by tightening the adjusting nut.
3. Pedal Backlash Adjustment. The approximate value is 34-43mm (measured with a ruler when the pneumatic system is empty).
clutch
Electrical equipment
Single wire on-board network provides power for 24 V on-board consumers. Two 6-ST-182 or 6-ST-190 batteries and an alternator with a built-in voltage regulator provide DC power.
device
MAZ-5551 without a sleeping place is much more spacious than KAMAZ trucks. Thanks to conveniently located handrails and steps, it is extremely easy to enter the cab of the truck. Ergonomics of the driver’s cab is not the strong point of the truck. Although the seat cushion can move, and the steering column is adjustable in two planes, we can not speak about the comfort of the driver. The cabin has a good visibility, but the discomfort leads to increased fatigue, which is especially noticeable on long trips. The huge steering wheel also does not add comfort, because low drivers have to lean forward to turn.
Dashboard MAZ-5551 is very informative and practical. However, there are some shortcomings. The light display has a low brightness, so it is not visible in the daytime.
However, there are much better solutions in the cab of the truck. The location of the relay and fuse box behind the dashboard is very practical and makes it easier to get close. Efficient heating, sunroof and overhead lights in the cab contribute to comfortable driving.
Unlike KAMAZ models, MAZ-5551 has only one passenger seat. In the middle of the cab, between the seat of the front passenger and driver, there is a shelf for storage of bottles, various things and documents. There is also a drawer for cigarettes. But there is no cigarette lighter and ashtray in the cab.
Thanks to the large rear view mirrors, the visibility and safety of driving MAZ-5551 is increased.
The driver’s seat is cushioned and adjustable in several directions. However, the cabin is still not really comfortable, as the vehicle has no shock absorption system. The passenger seat is attached directly to the floor.
The cabin .
What interesting things have the designers done to improve ergonomics and ease of operation of MAZ? There are a lot of changes, and all of them are very nice. The cabin is comfortable and spacious. Even without a sleeping place two passengers can easily stay here.
Well-designed handrails and steps make it easy to get into the cab. The seat can be moved and adjusted – unfortunately, only the passenger seat. In the 1990s, not every car had adjustable steering wheel, but MAZ-5551 has it. The first drawback is also noticed in the cabin – the steering wheel is too big. If you are not large, you have to lean forward a little bit every time you turn. Such an innovation can hardly be considered as a convenience.
The dashboard leaves a double impression. On the one hand, it is informative enough, on the other hand it has weak brightness, therefore separate elements are practical in day time. A conveniently located safe is an undeniable advantage of MAZ-5551. As well as an effective heating, which perfectly copes with its task even in severe frosts. There is a small object between the passenger and driver, where you can hide various small items – documents, keys, mineral water, etc.
Weight parameters and load distribution
- Payload – 8500 kg;
- Unladen weight – 7580 kg;
- Load distribution – front axle – 4130 kg, rear axle – 3450 kg;
- Gross vehicle weight – 16230 kg;
- Distribution of load with gross weight – front axle 5980 kg, rear axle 10250 kg;
Dynamical performance
- Maximum speed specified by the manufacturer is 85 km/h;
- Acceleration time to 60 km/h – 50 seconds;
- Overcoming of the vehicle at 50 km/h – 850 m;
- The maximum angle of climbing a-25 degrees;
- Venderadius – on the outer wheel – 7,9 m, total 8,6 m;
- Time of work of a design at revolutions of the engine 1900 rpm lifting – 15 seconds, descending empty – 10 seconds;
- Angle of body slope – 50*.
Linear and volumetric parameters
- Length – 5990 mm;
- Width – 2500 mm;
- Height – 2925 mm;
- Height with fully raised structure – rear ripper 4850 mm, side tipper 3850 mm;
- Wheel stand – 3950 mm;
- Loading area – 3860 x 2265 x 630 mm;
- Spacing – 270 mm;
- Volume of the body – 5,3 m3 in the basic version, up to 12.5 m3 in different modifications;
Functions and operation
MAZ-5551 is a brainchild of the Soviet automobile industry, and the principle of minimalism can be seen in the design of the cab. In contrast to its predecessor, the truck has a more advanced hydraulic (with manual drive) tilt cab, panoramic windshield and enlarged mirrors. Drivers’ complaints were that the instrument lights were not sufficiently informative during the day, and that the seats were not very comfortable. It was also difficult to move off in first gear with a loaded car. But it was only for models with YAMZ-236P transmission and not enough powerful 180 hp engine. In 1998 the design of the cabin was changed, and the improvement of the vehicle continues to this day. An anti-lock braking system (ABS), sleeper compartment, air conditioning and autonomous air heating are available as options for the vehicle. Modern modifications MAZ-5551 are equipped with YAMZ-53623.10 engines, which ensure compliance with environmental standards EURO-5. Some trucks are equipped with German Deutz engines and transmissions ZF, but these trucks are more expensive.
The dashboard and controls
The truck is started by turning the key in the lock on the underside of the steering column.
The turn signal and low/high beam switches are under the left hand. The turn indicators are switched horizontally. Permanent or momentary activation is possible. The headlights are controlled in the vertical plane. A buzzer is activated when the knob is squeezed at the end.
The wiper and washer switch is located to the right of the steering column.
On the dashboard in front of the driver are the speedometer, tachometer, and instrument cluster for fuel level, coolant temperature, oil pressure, and voltage.
Here are also the control lamps and switches of lighting devices, as well as the button for disconnecting the inter-axle differential and ABS control lamps (if the truck is equipped with this stabilization system).
Nearby warning lights on the instrument panel are:
- coolant temperature (illuminated at 105±5°C),
- emergency oil pressure,
- fuel level (illuminated when the fuel tank is 16-20% full or lower),
- air pressure in brake system,
- contamination of the oil filter and others.
instrument panel
To operate the vehicle
To warm up the engine or inflate the tires, press, hold, and release the fuel pedal. Warm the engine up at minimum speed with a gradual increase to medium speed. Do not move until the coolant is at least 40C.
Do not use constant fuel while driving!
The parking brake is activated by moving the lever to the rear position. When it returns to the front position it is disengaged. In intermediate positions the auxiliary brake is applied.
Gearbox YAMZ-236P – five-stage with synchronizers on 2-3 and 4-5 gears. Gear shifting is carried out as follows:
To lift the platform, it is necessary to turn the control valve to the “lifting” position. Other rules: stopping, descending and transporting.
When starting on a slippery surface, it is necessary to engage the differential lock when passing difficult road sections. This should be done with the vehicle stationary or at speeds up to 10 km/h.
Going into a corner with a locked differential is dangerous. It reduces steering ability and leads to increased wear of the drive train! When the differential is locked, the corresponding symbol on the instrument panel lights up orange.
To operate the vehicle
safety
Working with a dump truck involves the risk of injury and accidents. To reduce these risks and the likelihood of mishaps, a number of safety rules should be followed. Here are some of them.
- Do not stand in front of the cab while it is being lifted or lowered, and do not drive without a rope securing the cab or with the tipping mechanism open.
- Do not adjust the driver’s seat while driving.
- Do not operate the machine with the platform raised and do not lower the loaded platform.
Detailed instructions on safe operation and includes the MAZ-5551 Operation Manual. There you will also find maintenance requirements and basic troubleshooting recommendations, as well as a detailed description of the design and assemblies of the dump truck.
Also, due to the popularity of this vehicle, there are many repair manuals on sale, and the purchase of spare parts will not cause difficulties.
MAZ-5551: technical characteristics
Almost since the beginning of mass production of MAZ-5551 dump trucks in 1985 and to this day, this car can be found on almost every construction site in Russia and other republics of the former Soviet Union. MAZ-5551 – a compact (with a capacity of 8-10 tons), maneuverable and inexpensive car that has become very widespread, mainly in the form of dump trucks. About the design features and specific application of MAZ-5551 – more.
Scope of MAZ-5551
This simple and unpretentious truck is ideal for tasks such as delivery of gravel, sand and other bulk materials, removal of construction debris, etc. Also MAZ-5551, with a properly prepared body, turned out to be a good grain carrier.
The design of this truck is not innovative. In fact, the basis of the car is a platform, developed back in 1958 by Minsk Automobile Plant. MAZ-5551 became the result of a serious modernization of its predecessor – 8-ton MAZ-5549. This is the “ancestor”. The “descendant” or “successor” of 5551 model MAZ is a truck MAZ-5336, which debuted in the 90s.
And what a successor can be, when MAZ-5551 in 2010s is one of the most popular Russian trucks in its class, successfully competing with KAMAZ and Chinese counterparts. And in the catalog of Minsk Automobile Plant, it is still listed as a current model in the current price list: see the “Production. Euro-3”. And it is the oldest of currently produced MAZ models.
The main advantages of MAZ-5551, which determined its continued success on the market, are reliability, productivity, ease of operation and, of course, low cost in comparison with competitors. That is all that is necessary for profitability, economic profitability of using machinery.
Other important advantages of MAZ-5551 are agility and maneuverability due to the small wheelbase and two-axle configuration of the truck. Therefore, it fits perfectly even in small construction sites.
Today some people talk about this (the most popular in its class) truck – “garbage”. Others prefer a more intricate, but essentially correct wording – “proven, economically reasonable solution”!
Maz today
Minsk Automobile Plant in the 21st century is an enterprise with a complete production cycle, the main site of which includes modern foundry, forging, mechanical assembly, thermal machining, forge-and-press, feathering, tooling stamping and other productions. MAZ unites thirteen plants in different cities of Belarus into a single industrial goldmine.
MAZ trucks are supplied to forty countries of the world: Europe (former socialist countries); Latin America, Africa, Middle East, Central and South-East Asia. The production capacity of Minsk Automobile Plant today is 35,000 units per year (trucks, buses, airline buses). More than 25 000 workers and other employees work at enterprises of MAZ holding.
To keep up with the times, the automobile plant produces vehicles complying with high international environmental standards (up to Euro-6 inclusive). But this, of course, has nothing to do with MAZ-5551 truck: this model is still focused mainly on GUS countries.
Design features, modifications of MAZ-5551
However, we can not say that this is the same MAZ-5551, which first came off the assembly line in 1985. Since then, the car has gone through a number of changes and improvements. And in 1998, the model has experienced a fairly serious redesign. The updated version of the most massive 8-ton Mulic dump truck received newly designed cabin – both outside and inside.
The cabin has become much more spacious, has a more advanced tilting mechanism for maintenance and repair of the engine. The engine also changed, which together with the strengthening of design of the truck increased capacity by eight-ten tons.
The range of MAZ-5551 trucks is not very extensive. In addition to the popular “tipper” version, it also includes a universal chassis for recording of different buildings and special equipment. There is also a street articulation. Initially, MAZ-5551 dump trucks were equipped only with a tipping body with unloading, then they received a design with three-way unloading. For the northern and far-eastern regions the “HL” modification is produced. It is prepared to work at low temperatures up to 60 degrees Celsius.
- MAZ-5551 and MAZ-5551-020 – previous modifications, trough bucket with rear loading, with 180 hp diesel engine JAMZ-236. The only difference of the “020” modification is the increased volume of the loading part, due to the change of the initial number of pages. The other technical characteristics are identical;
- MAZ-5551 A2-320 – a more modern model, 10-ton mulch tipper with rear discharge, with 230 hp turbocharged engine JAMZ-236 / NE2.
- MAZ-5551 A3-4327-A model for transportation of loose goods or agricultural products with a large welded body (volume 12.5 m³) and unloading on three sides. The body has a folding sides, which allows loading from two sides.
- MAZ-5551 A2-325 – tipper for cargo transportation as a part of a road train, stable operation together with a trailer. MAZ-5551 A3-4327 also has a possibility of three-side unloading, but with a 5.5 m³ body.
- MAZ-5551 A2-340 tractor has a semi-automatic clutch with two degrees of freedom. It is designed for special vehicles and works in supply organizations, as a car towing, etc.
Technical features MAZ-5551
Mass-size characteristics
- Length: 5,990 m; Width: 2,500 m; Height (on the roof of the cabin): 2.925 m.
- Which BAZ: 3.30 m or 3.950 m.
- Street clearance: 280 mm (minimum under the front axle).
- Width of front wheels: 2.032 m; Width of rear wheels: 2.162 m on the outside and 1.422 m on the inside.
- Curb weight – 7,580 tons.
- Payload: 10 tons (in pre-1998 trucks – 8 tons).
- GVW is 16.230 tons.
- Distribution (with curb weight): 4,130 tons on the front axle; 3,450 tons on the rear axle;
- Distribution (gross weight): 5,980 tonnes front axle; 10,250 tonnes rear axle;
- Load platform dimensions: 3800 x 2269 x 630 mm.
- The angle of inclination to be overcome: 25 degrees;
- Radius of lift of outer wheel – 7,9 m; Radius of overall turn – 8,6 m.
- Volume of the body – from 5,5 to 12,5 cubic meters (with different sides height).
- Body lifting time is 15 seconds, lowering time of empty body – 10 seconds. Body lifting angle is 50 degrees.
MAZ-551 engines
MAZ-551 was originally installed on a V-shaped six-cylinder diesel engine model YMZ-236M2-1 Yaroslavl engine system. Some parameters of this engine: displacement – 11.15 liters; Power – 180 PS or 132 kW; Cylinder diameter – 130 mm; Maximum torque – 667 Nm; Frequency at max. Torque Torque-1250-1450 rpm; Minimum specific fuel consumption, 214 g/kWh (157 g/hp).
In the 90’s and 2000’s the atmospheric engines were replaced by more modern Yaroslavl diesel engines, equipped with a turbocharging system. A number of diesel engines were installed on MAZ-5551. And not only domestic, but also imported diesels – from Deutz and Kamminz. For a clear reason, “got accustomed”, “got used”, one of the main advantages of this truck is its cheapness.
In addition, the YMZ engines performed their functions perfectly. From Yaroslavl diesel engines, the most important and used now on MAZ-5551 A2 are YAMZ-236nu-2 and YAMZ-6563-3-3.
These are four-stroke diesel engines with an ignition capacity of 11.15 liters; with direct fuel injection with turbocharging, liquid cooling, liquid oil heat exchanger, mechanical rotary frequency regulator, with medium-cooled charge air in the air-to-air heat exchanger in the vehicle.
YaMZ-236NU-2 is a representative of the classical family of six-cylinder V-type diesel engines developed by Yaroslavl Power Plant and equipped with a turbocharger, specially adapted for the use on MAZ trucks.
Its parameters: Power – 230 hp (or 169 kW); Maximum torque – 882 Nm (90 kgps); Maximum torque is 1200-1400 min-1; Minimum specific fuel consumption – 206 g/kWh (152 g/hp).
YAMZ-6563.10 engine was also designed specifically for installation on flatbed trucks, tractors, flatbed bodies, MAZ chassis with 4×2 axle arrangements. The truck trains are based on 32 tons. Its features: Power – 230 hp (or 169 kW); Maximum torque – 882 Nm (90 kgps); Frequency with a maximum torque is 1100-1300 min-1; Minimum specific fuel consumption – 200 g/kWh (147 g/hp).
According to the manufacturer, the actual fuel consumption in the combined cycle is 22 liters per 100 kilometers. Volume of the fuel tank is 200 liters.
Transmission and hydraulics of MAZ-5551.
Yaroslavl gearbox YAMZ-236P, which is installed on MAZ trucks with a diesel engine, is also quite reliable and proven. This is a 5-speed manual gearbox with synchronizers on 2-3 and 4-5 gears. The gear ratio is 7.79.
In the updated versions of MAZ 5551 the gearbox has received a number of significant design changes. Revision of the shifting mechanism from the lever to the gearbox made it possible to significantly shorten the lever, which facilitated the work of the driver.
MAZ-5551 is equipped with a double-plate friction clutch, which is traditional for domestic trucks of this class and also made by Yaroslavl Motor Plant. Elements of this unit are subject to wear due to significant overloads during operation and require periodic maintenance. Brake system: drum brakes with ABS. Tire size: 12.00R20.
The hydraulic system of MAZ-5551 truck consists of a pump and a three-stage telescopic hydraulic cylinder, which provides tipping of the body. It is controlled remotely from the cabin.
Part of the hydraulic system is a power steering, which not only saves the driver from unnecessary stress, but also allows taking full advantage of good maneuverability.
Dump Truck MAZ-5551
MAZ-5551 is equipped with an all-metal body. The opening of the back door and tipping of the body is in automatic mode. Only one-way unloading was possible for this model in the past years. In addition, optional special systems allowed the unloading in three directions.
Not an unreasonable technical solution implemented in this model is heating of the body floor with exhaust gases. This allows the tipping mechanism without problems, even in harsh conditions with severe frosts.
The MAZ-5551 tipping mechanism is located under the platform. The tipping mechanism, as well as at the majority of modern dump trucks, is a hydraulic with pneumatic control. Telescopic hydraulic cylinder of variable capacity consists of three sequentially extending links – this design allows for sufficient capacity in the folded condition with a small weight and dimensions. Its main disadvantage is considerable complexity, as well as the possibility of serious clogging of the tightly fitting joints.
A safety device is provided in the hydraulic cylinder control valve to increase safety during unloading. It does not allow the platform to be fully lifted when overloading more than 1.5 tons. Lifting time of a loaded body at 1900 rpm of an engine crankshaft is 15 seconds; descending time of an empty body – 10 seconds.
As an additional equipment on MAZ-5551 is installed: a platform with an increased volume – 8.3 cubic meters; engine heater – PJD-30.
MAZ-5551 is very maneuverable and turns in two steps, even on narrow roads. Due to the transverse stabilizer bar it provides an increased stability on turns.
MAZ-5551 cabin
The cabin of the most popular dump truck MAZ differs from the previous models of the Belarusian trucks. The shape of headlights, grille, and shape of cabin has changed – the time of a slightly rounded shape is gone.
The type of the windshield has changed – it became not fluctuating, but panoramic. There is a new roof spoiler. The appearance of the mass dump truck is not burdened with manifestations of modern design, as if it is a “worker”, a vehicle for intensive work and only for work.
The interior of the cab has also changed, control levers and steering wheel have been changed. Getting into the cockpit of MAZ-5551 is easy and comfortable, thanks to neatly placed handrails and steps. Although the seat cushion moves, and the steering column agrees in two planes, we can not talk about the true comfort of the driver.
Trembling! The driver’s seat partially compensates for the lack of shock absorbers in the cabin. The passenger is less lucky – his seat is fixed directly to the floor and has no adjustments.
In contrast to the KAMAZ models, MAZ-5551 has only one passenger seat. In the middle of the cabin, between the passenger and driver’s seats, there is a shelf for storage of various things and documents. The interior has a good visibility, also due to the large rear view mirrors. The steering wheel, especially at first glance, is too big, and to turn it the unseen driver with his body has to constantly pitch forward with his body. But this is a matter of habit.
To lower the cab, MAZ designers took the disadvantages of previously used spring mechanism and equipped them with a hydraulic drive. Hydraulic control of the cab is located under the radiator grille. This location is due to the fact that the driver is reminded that it is impossible to enlarge the cabin without an open radiator grille.
Reviews of drivers and owners of MAZ-5551
Ratings ruled the masses – a Mazovian dump truck with a coil. Turning and maneuverable, economical and profitable, simple, “as a chair”, in operation and maintenance – these positive properties of this model are found by almost all drivers and owners of the truck.
This vehicle is equipped with a durable, painful and not – resistant engine. Productive, unpretentious and reliable. “After working on this car for 5 years, you start treating it like your own.
However, MAZ-5551 requires regular attention and maintenance. For example, the braking system, equipped with various safety valves, does not let you relax. Every air leak affects your wallet, because you have to spend extra fuel to maintain constant air pressure in the working area.
That’s why all air connections need to be sealed immediately with rubber rings and gaskets, and tubing needs to be routed with rubber weights.
According to many drivers, the compressor on MAZ-551 is weak, the air has to be constantly pumped up. On a winter road the truck shows a weak cross: “A little ice cream – and everything stands still, shakes all the time, no locks, nothing helps”. In the summer, the Cros s-Country shows superiority: “Rows through any mud like a tank”; “Had to drive on forest roads, so this car gets through everywhere. “
The work of the transmission is a source of criticism. Namely: A loaded MAZ-5551 is rather difficult to start up, especially on loose and unconsolidated ground. The short first gear makes the acceleration dynamics extremely sluggish. But on a flat street, the dump truck starts well from the second gear.
Everyone reacts negatively to the unnecessary cab: “It shakes, everything flies around the cab”. In this regard, all drivers and owners unanimously agree that MAZ-5551 is unsuitable for a long time and remove the “race”.
The following conclusion can be made: The truck has an optimal design for short-distance transportation. It is a versatile and reliable “working cattle”, able to do its job in almost any conditions.
Price of MAZ-5551
The cost of a new MAZ-5551 starts at 2,500,000 rubles. Due to the widespread availability of this truck on open license plates of the former USSR, in almost every region it is not difficult to find options for buying a used MAZ-55551 in technically serviceable condition as well.
At the same time for MAZ-5551 90th years of manufacture are asked from 200 to 400,000 rubles; For cars two thousand years of manufacture price ranges from 400,000 to a million rubles, depending on the specific year of manufacture, mileage and technical condition.
