The dump truck is a hard worker, quite a worthy representative of this kind of special vehicles. And, despite the already quite advanced age of the model, it is still a good competitor to Tatras and KamAZs of a similar design. At least in terms of price-quality ratio. And maintainability, given the close economic ties with the Republic of Belarus, in conditions of construction sites with intensive operation, is also not the last priority.
A little about the history of the model and its place in the plant’s assortment
The closest “relatives” and predecessors of the MAZ-5549 in the model range of the Minsk Automobile Plant are the MAZ-503A and MAZ-5335 trucks. The successor is a new generation dump truck MAZ-5551. Despite the fact that the latest model began to be produced in Minsk in 1985, the more archaic MAZ-5549, in comparison, stayed on the factory assembly line for another 5 years and rolled off it until 1990 inclusive. The demand for these cars remained stable during the emerging perestroika years.
Compared to previous models, on the MAZ-5549 the headlights were moved for the first time from the cab to the front bumper. This was done in accordance with the requirements of the new international safety standard for the placement of lighting equipment on trucks. A new decorative plastic radiator grille was installed on the familiar “lobed” MAZ cab that remained the same. In place of the previous headlights there are special plastic plugs, and in them there are combined side lights with direction indicators.
MAZ-5549, a two-axle compact dump truck, quickly became in demand at construction sites throughout the country. Everywhere it was used to transport soil, sand, crushed stone, and all kinds of building materials. The truck had excellent maneuverability on construction sites of any size. What can I say: the standard carrying capacity of 8 tons was strictly observed in few places - the sides were added, the body was systematically overloaded. The frame steadfastly withstood any overload... For the time being.
The effective use of a dump truck is noted when working with excavators with a bucket capacity of 0.5 to 1 m3 - for developing, moving and dumping soil, crushed stone and sand, including from quarries to construction sites.
Historical reference
As a basic model with a wide range of actions, this car was conceptually conceived back in the early 70s of the last century. The result of the work of the Minsk Automobile Plant Design Bureau was the appearance in 1977 of the MAZ 5549 model, which, with minor modifications, was produced until 1990. Compared to previous modifications, the MAZ headlights of this series were placed in the recesses of a cast steel bumper, which complied with international safety requirements for lighting technology, and in their former place, blocks with side lights and turn signals were installed in the “lobed” cab typical of MAZs. The same layout was retained in later models.
It is a compact and highly maneuverable two-axle dump truck with a 4x2 wheel arrangement, with a rear unloading body and an automatically opening and closing tailgate. Thanks to its relatively low price and ease of operation and repair, it has become in demand at construction sites throughout the country.
MAZ-5549 truck engine
The car uses a six-cylinder four-stroke 12-valve diesel engine YaMZ-236 with a V-shaped cylinder arrangement at an angle of 90 degrees. Working volume – 11.15 liters; power 180 horsepower (132 kW), at a crankshaft speed of 2100 rpm. Torque – 667 N.m (68 kgf.m), at 1500 rpm. The compression ratio is 16.5. The minimum idle speed is 450-550 rpm. The MAZ-5549 was not equipped with a turbocharged, but with a conventional naturally aspirated version of the YaMZ-236 / YaMZ-236M / YaMZ-236M2 (Euro-0) engine.
The speed controller is centrifugal, all-mode. The pressure in the lubrication system at nominal speed is 4-7 kgf/cm3. There are two oil filters. cooling system – liquid, closed type, with forced circulation of coolant; oil cooling - using an air-type oil cooler. The air filter is inertia-fine, with a contact element. The YaMZ-236 engine is equipped with a PZD-44 liquid starting heater.
Description
The Minsk dump truck was driven by a V-shaped 4-stroke 6-cylinder 12-valve naturally aspirated power unit YaMZ-236. It was equipped with an all-mode centrifugal speed controller, two oil filters, a forced liquid cooling system and an inertia-oil air filter. For start-up in the cold season, a PZD-44 liquid heater was used.
Clutch YaMZ-236K – double-disc, friction, dry. The YaMZ-236P gearbox is mechanical, with 5 forward speeds, plus 1 reverse, with synchronizers. The cardan is open, with a tubular middle part. The steering is made with a gear pair and a screw transmission, as well as a hydraulic booster. Drum brakes with pneumatic drive. There is a compression retarder with a flap in the muffler and a manual parking brake.
Transmission MAZ-5549
This engine was equipped with a clutch model YaMZ-236K - dry, friction, double-disc. Manual gearbox - YaMZ-236P, five-speed, three-way, with synchronizers in II-III and IV-V gears. gear ratios are as follows: 1 – 5.26; 2 – 2.90; 3 – 1.52; 4 – 1.00; 5 – 0.66; rear – 5.48.
The cardan shaft is open type, the middle part of the shaft is tubular. Hinges with needle bearings. The main gear is a pair of bevel gears with a spiral tooth. Wheel drive – cylindrical spur gears (central, three satellites and internal ring gear). The total rear axle ratio is 8.28.
Control mechanisms
The steering mechanism is with a screw transmission and a gear pair. The steering gear ratio is 23.6. The steering mechanism is equipped with a hydraulic booster. In the MAZ-5549, the power cylinder of the amplifier is an integral part of the steering gear (trapezium). The maximum steering angle of the front wheels is 38 degrees.
The braking system consists of front and rear drum mechanisms with pneumatic drive. Foot brake drive – with separate braking of the front and rear wheels. The air compressor is two-cylinder, liquid-cooled. The hand brake is central, also of shoe type, located on the flange of the drive gear of the rear axle. The retarder is a compression brake with a rotating flap in the exhaust system.
Device
The signature feature of the MAZ-5549 model is the rounded shape of the cabin. This type is familiar to many modern motorists from childhood. The main feature of the truck is the headlights mounted in the front bumper, as well as turn signals installed in the place where the headlights are traditionally located. There are no panoramic windows here, like the latest products of the Minsk Automobile Plant. The “chips” of the model include a double windshield.
The steering wheel of the car is located almost vertically. Its rim is 3-spoke and very thin. The steering wheel itself is supplemented with power steering.
Suspension and chassis
The front suspension consists of longitudinal semi-elliptic springs, the rear suspension is equipped with additional spring parts (sprung). The front suspension of the MAZ-5549 truck is equipped with double-acting hydraulic shock absorbers.
All MAZ-5549 spring sheets were made from strip spring steel 60 C2. To increase fatigue strength, the sheets were heat-treated and hardened in molds that fixed the specified curvature of the sheet. The hardness of the sheets after heat treatment is HB 363–444. After heat treatment, the first three leaf springs on the concave side were also shot blasted.
All springs have sheets in the center that are tightened with a center bolt, which makes their assembly easier. To prevent the leaf springs from moving apart, they were tightened with several clamps made of strip steel.
MAZ-5549 wheels are discless, with side and locking rings. Tires: 300-508R (11.00-20) NS-14, model I-68A. Installation of tires of other models is possible. For example, the official operating manual for the MAZ-5549 refers to 302-508 (12.00-20) models IYAV-12A and IYAV-12B, as well as 320-508r (12.00-20) models I-109B.
The dump truck can climb an upward slope of 25 degrees. The minimum turning circle is 15 meters.
Loading platform
The cargo platform on the MAZ-5549 is metal, welded, with an automatically opening and closing tailgate. The dump platform is equipped with a body lifting mechanism. It is hydraulic, single-cylinder, telescopic type, with direct action of the cylinder on the platform.
The dumping mechanism is controlled from the driver's cabin; it is electro-pneumatic. The pneumatic actuator acts on the power take-off and control valve. Unloading is done only backwards, with a maximum body elevation angle of 55 degrees. The hydraulic system of the lifting mechanism also includes a special valve that provides shaking of the body at the very end of its upward lift.
Technical specifications in numbers
- Overall dimensions: length – 7.25 m; width – 2.5 m; height – 2.72 m.
- Wheelbase - 3.4 m.
- Track width: front – 1.97 m; rear – 1.865 m (between the middles of the double slopes).
- Ground clearance – 270 mm.
- Minimum turning radius – 7.5 m (along the track of the front outer wheel); 8.5 m (along the bumper).
- Curb weight - 7.225 tons. Gross weight - 15.375 tons.
- Weight distribution along the axles: 3.6 t – on the front axle; 3.625 t – to the rear axle (without load); 5.375 t - on the front axle; 10 t – on the rear axle (with full load).
- Standard load capacity on paved roads is 8 tons.
- Body volume, without extensions - 5.7 cubic meters.
- Approach angle (with full load): front – 24 degrees; rear departure angle is 48 degrees.
- The load lifting angle is 55 degrees.
- The capacity of the diesel fuel tank is 200 liters.
- The capacity of the cooling system is 30 liters.
- The capacity of the engine lubrication system is 25 liters.
- Maximum speed (with full load, on a flat, dry road) is 75 km/h.
- The standard control diesel fuel consumption is 22 liters per 100 km.
- Braking distance at a speed of 40 km/h is 18 m.
Cabin of MAZ-5549 dump truck
The MAZ-5549 trucks were equipped with a unified MAZ cab of those times. This is a two-seater all-metal welded cab with side doors that does not have a sleeping place behind the driver and passenger seats. A berth on a compact construction and industrial truck is, of course, not a typical and hardly necessary thing for a vehicle of this class.
For unobstructed and convenient access to the engine, the cabin tilts forward, relative to the front hinges. There is no single panoramic windshield in this cabin yet. There are two windshields here, with a separation between them, like on ancient MAZs and other trucks. The driver's seat is mounted on a sprung stand, and the passenger seat is simply rigidly attached to the cabin floor.
Video
Several significant modifications were created on the basis of the MAZ-5549. The car did not become the most popular truck on the Soviet market, but its reliability and unpretentiousness made it very popular. Many of these machines are still in active use today. The main area of application of the vehicle is the transportation of various goods over long and medium distances.
MAZ-5549 was very far from perfect. The design of the car itself and the cabin provided the driver and passenger with a minimum of comfort. Some nodes turned out to be located rather poorly and did not allow us to quickly get to them. However, the reliability, low cost and maintainability of this truck did their job. Domestic consumers chose it even if there were more advanced and convenient options.
For this model, the expression “car of the last century” is true. However, it is definitely too early for the truck to be scrapped, since it is capable of much more, which determines the high demand for it.
Reviews of the MAZ-5549 dump truck
The MAZ-5549 could never be called a comfortable car for work - neither during the years of its production, nor, especially, in the modern era. However, the weak, even for a dump truck, comfort in the cabin, thoughtful acceleration and heavy gear shifting with a tight lever did not bother consumers of this equipment. After all, these obvious shortcomings were compensated by the practicality and functionality of the machine: low cost of purchase and further maintenance, extreme endurance and reliability, even under conditions of everyday intensive use.
According to driver reviews, the MAZ-5549 cabin is quite noisy and shaking, especially when driving with an empty body - on bumps in the cabin, literally, “everything flies.” It’s good that the driver’s seat is sprung, but it’s still a bit harsh. The steering column of the truck is located almost vertically, and the steering wheel, accordingly, is horizontal. The three-spoke steering wheel rim is quite thin. However, thanks to the effective hydraulic booster, working with the steering wheel is quite comfortable.
The gears must be changed with the clutch disengaged by smoothly pressing the lever, without jerking. Having felt the resistance of the lever (the moment of contact of the conical surfaces of the synchronizers), you need to continue smooth pressure on it until the gear is fully engaged. Sudden movements of the lever do not help, but interfere with the correct gear selection. It is recommended to move away without a load from the second gear, and with a load - only from the first.
As experienced drivers note in their reviews, the MAZ-5549 dump truck really “loves” to dig and start with slipping, especially if it has an empty body. On regular road tires this leads to the fact that sometimes even wet grass or slight icing becomes a small obstacle for it.
Therefore, when loading sand or soil, the main thing is to successfully leave the quarry. “This MAZ two-axle truck really loves to dig. He digs everywhere he stands. Sometimes, when you can’t get out on your own, the excavator operator pushes with a bucket. That is why many dump trucks have a crumpled tailgate,” one of the owners and, at the same time, drivers of a used MAZ-5549 shares his impressions, “it can be especially difficult if loading is carried out on a hill with a good slope and you need to start with the load up. It’s easier for those who have a box with a divider.”
And when unloading, the same experienced MAZ specialist says, the main thing is to unload on a level area. If the dump truck stands crooked, there is a risk of breaking the frame. Therefore, cracks on the frame of the MAZ-5549 are not uncommon: these are the consequences of systematic overloads and “crooked” unloading.
The cross-country ability of the two-axle MAZ-5549 is poor, so for the most part it is a purely “city dweller”. Here he always shows himself at his best in terms of maneuverability and versatility of useful applications.
Without a doubt, the purchase of a MAZ-5549 dump truck or work on it can only be recommended to extremely experienced and qualified “old-school” drivers who are ready for any surprises at work and can carry out most of the repairs themselves. However, there is no reason to accuse MAZ-5549 dump trucks of any unreliability or tendency to frequent breakdowns: it’s just the opposite. It’s just that the years take their toll, and the remaining “in service” trucks of a given model have often already exhausted their regular service life several times; are often “cooked/overcooked” due to systematic overload.
Most memories of working on MAZ-5549 dump trucks are positive. This machine is simple and reliable, with a trouble-free and durable engine.
Scope of application
The main area of application of the dump truck was work on construction sites and small quarries. The characteristics of the MAZ-5549 made it possible to use the chassis as a base for installing various superstructures - concrete mixers and other construction equipment.
A distinctive feature of the MAZ-500 and 5335 family of vehicles is their “indestructible” design and undemanding quality of service. The cost of the machine itself is low with a high prevalence of new and used spare parts. For these reasons, cars are still used on construction sites, despite the complete lack of comfort for the driver.
