Modern urban management cannot be imagined without specialized equipment that ensures clean streets and timely waste removal. Among the variety of models, a special place occupies machine for municipal services MUP 351 TST, which has proven itself to be a reliable and productive tool in the hands of utilities. This vacuum vehicle is designed for collecting liquid sewage, flushing and cleaning sewer wells, as well as for transporting and draining the collected liquid to disposal sites.
Unlike standard vacuum trucks, this modification is often based on a reinforced chassis and is equipped with more powerful pumping units, which allows it to operate under high-intensity load conditions. Equipment of this class requires a competent approach to operation, since not only the efficiency of the team’s work, but also the environmental safety of the area depends on the serviceability of its systems. Understanding vacuum and hydraulics is key for any operator or mechanic.
Owners and operators of this special equipment are often faced with the need to independently diagnose minor faults so as not to interrupt the work process due to trivial reasons. The main working part of the machine is a vacuum pump of the VK-6M type or similar, creating a vacuum of up to 0.05 MPa. It is this parameter that determines the suction speed and the ability to lift liquid from great depths. In this article we will analyze in detail the device, maintenance features and typical problems that you may encounter when operating this model.
Technical characteristics and design of the vacuum system
Structurally machine for municipal services MUP 351 TST is a complex engineering system mounted on a truck chassis, most often KAMAZ or URAL models. The basis of the entire system is a cylindrical or elliptical tank, divided into compartments for clean and dirty water, if we are talking about a combined machine, or a single volume for waste collection. The most important element is vacuum pump, which is driven by the car engine through a cardan transmission and gearbox.
The efficiency of operation directly depends on the condition of the pump blades and the tightness of the connections. During long-term operation, the gaps between the rotor and the housing may increase, which leads to a drop in performance. Pipe system made of wear-resistant materials that are resistant to aggressive environments, however, rubber seals require regular inspection. Particular attention should be paid to the sediment filter, which protects the pump from solids.
Features of pump operation at low temperatures
When operating in winter, it is necessary to warm up the pump gearbox before turning it on at full power. Cold oil in the gearbox can lead to increased wear of the gears and jamming of the shafts in the first minutes of operation.
The hydraulic system, responsible for controlling valves and rotators, also plays a critical role. The pressure in the hydraulic system must strictly correspond to the passport data specified in Operating manual. Excessive pressure can lead to rupture of the hoses, and insufficient pressure can lead to incorrect operation of the mechanisms.
- 🚜 Pump capacity: ranges from 5000 to 6500 m³/h depending on the modification and engine speed.
- 💧 Tank volume: varies between 3500–4000 liters, which is optimal for maneuverability in urban environments.
- ⚙️ Drive type: mechanical from the power take-off (PTO) or hydraulic, ensuring smooth activation.
Regularly checking the oil level in the vacuum pump gearbox is the easiest way to prevent costly major overhauls of the unit.
Operating rules and preparation for work
Before starting the working day, the operator must carry out a thorough external inspection technology. This is not just a formality, but a necessary security measure. It is necessary to check the integrity of the tank, the absence of leaks of hydraulic fluid and oil, as well as the reliability of the suction hose. Working with faulty equipment is strictly prohibited, as it can lead to emergency situations at the site.
The tank filling process must be monitored visually or using level sensors, if installed. Overfilling the tank threatens with liquid entering the vacuum pump, which is fatal for it. Separatormounted on the neck must be clean to protect the pump group. If the machine is equipped with a flushing system, you need to monitor the water level in the clean water tank.
☑️ Daily check before departure
When working in winter, it is necessary to use special antifreeze or add hot water to the tank to prevent freezing of sewage residues. Icing shut-off valves can completely paralyze the operation of the machine. After draining the contents into the sewer, it is necessary to rinse the tank and pipelines with clean water to avoid corrosion and the formation of hard deposits on the walls.
⚠️ Attention: Never open the rear shutter of the tank without making sure that the vehicle is on level ground and secured with the parking brake. Spontaneous release of residual liquid may result in personal injury or property damage.
Typical faults and methods for their elimination
During intensive use machine for municipal services MUP 351 TST may show various signs of malfunction. The most common problem is reduced vacuum pump performance. This may be caused by wear of the graphite blades, a leak in the suction hose, or a clogged filter. Diagnostics starts with checking rarefaction in the tank using a pressure gauge.
If the pump makes extraneous noise or knocking, this is a signal that the bearings are damaged or a foreign object has entered the working chamber. In such cases, stop the engine immediately and troubleshooting node. Ignoring these symptoms can lead to jamming of the pump and breakage of the driveline, which will entail complex and expensive repairs.
Problems with the hydraulic system often manifest themselves in the form of slow movement of cylinder rods or spontaneous lowering of mechanisms. The cause may be a low fluid level, air in the system, or worn o-rings in the hydraulic distributor. Changing hydraulic oil must be carried out strictly according to regulations, since old oil loses its lubricating properties and contributes to corrosion of internal surfaces.
| Malfunction | Probable Cause | Remedy |
|---|---|---|
| The pump hums, but does not pump | Wear of blades or violation of clearances | Replacing blades, adjusting gaps |
| Oil leak from gearbox | Destruction of seals or gaskets | Replacing seals, tightening bolts |
| Driveshaft vibration | Unbalanced or worn crosspieces | Shaft balancing, replacement of crosspieces |
| The rear shutter does not rise | Insufficient pressure in the hydraulic system | Checking the power steering pump, changing the oil |
Seasonal maintenance and conservation
Seasonality plays a huge role in the lifecycle of municipal equipment. Machine for municipal services MUP 351 TST requires specific preparation for the winter period. In addition to replacing technical fluids with frost-resistant analogues, it is necessary to check the operation of the tank heater, if it is provided for in the design. The thermal insulation of pipelines must be intact, without ruptures or damage.
In summer, the main emphasis is on the engine cooling system and hydraulics, which operate at elevated temperatures. Hydraulic oil overheating leads to its rapid oxidation and loss of working properties. Radiators must be free of lint, dust and dirt to ensure effective heat transfer.
To extend the life of rubber seals in winter, lubricate them with silicone grease before starting a work shift. This will prevent cracking and loss of elasticity.
If equipment is placed in long-term storage, for example, for the winter when there is no work, it is necessary to drain all liquids, lubricate exposed metal surfaces with preservation grease and install the machine in a dry room. tank must be thoroughly washed and dried to prevent the development of corrosion from the inside. It is better to raise the wheels on stands to remove the load from the tires.
⚠️ Attention: When preserving equipment, do not leave the tank valves in a closed position under spring pressure. This can lead to metal fatigue and deformation of the sealing surfaces, causing future leaks.
Hydraulic system: diagnostics and repair
Hydraulics in a car MUP 351 TST is the circulatory system that sets in motion all the actuators. The main element here is a gear pump, which creates the necessary pressure. A common problem is air getting into the system, which leads to “freezing” of the mechanisms and a characteristic whistle. Bleeding the system should be carried out with the engine running with careful movement of the cylinder rods from extreme to extreme position.
Hydraulic oil fine filters require regular replacement. A clogged filter causes a drop in pressure and can lead to pump seals being squeezed out. Hydraulic oil quality must correspond to the season: in summer, oil with a higher viscosity is used, in winter - with a lower one. Mixing oils of different brands and manufacturers is not recommended, as this may cause a chemical reaction and sedimentation.
If leaks are found on the hydraulic hoses, they must be replaced immediately. Working with damaged hoses under high pressure (up to 16 MPa and above) is deadly. A jet of oil released under pressure can pierce the skin and cause serious poisoning or injury.
- 🔧 System pressure: must be maintained in the range of 10–14 MPa for the correct operation of all mechanisms.
- 🛢️ Oil change: performed every 500 operating hours or once a year, whichever comes first.
- 🌡️ Temperature: The operating temperature of the oil should not exceed 80°C, otherwise accelerated aging of the fluid begins.
How to check the tightness of a hydraulic cylinder?
To check the tightness of the piston group of a hydraulic cylinder, it is necessary to fix the rod in the middle position under load. If the rod spontaneously extends or retracts, it means that the piston cuffs are worn out and require replacement.
Safety issues and environmental regulations
Operation of special equipment such as machine for municipal services MUP 351 TST, is strictly regulated by environmental standards. Draining the contents of a tank into places not intended for this purpose (storm drains, reservoirs, soil) is prohibited by law and entails huge fines. Control over the drainage site rests entirely with the machine operator. Modern vehicles can be equipped with GLONASS/GPS systems and rear gate opening sensors to control routes.
Operator safety also comes first. When working with vacuum systems, there is a risk of poisoning by hydrogen sulfide and methane vapors that are released from sewage. Work must be carried out in personal protective equipment, and, if necessary, using a gas mask. Ventilation tanks before lowering people inside (if required by work regulations) is mandatory.
During transportation, the machine is an oversized load, so it is necessary to strictly follow the traffic rules, turn on the orange flashing lights and observe the speed limit. Side lights must be in good working order, especially when working in the dark or in poor visibility conditions.
⚠️ Attention: It is prohibited to smoke or use open fire within a radius of 50 meters from the operating machine and the sewage drainage area, as the released gases form an explosive mixture with air.
Frequently asked questions (FAQ)
What is the service life of the vacuum pump on the MUP 351 TST machine?
The service life of a vacuum pump directly depends on the intensity of operation and the quality of maintenance. On average, when working in one shift and timely replacement of blades (every 500-700 operating hours), the pump life before major overhaul is about 3000-4000 operating hours. Using high-quality oil and filtering the intake air significantly extends the life of the unit.
Can this machine be used to pump out chemically active liquids?
Standard equipment of the machine MUP 351 TST Designed for domestic and industrial wastewater with neutral or weak acidity. Aggressive chemicals can quickly destroy rubber seals, tank coatings, and the pump itself. To work with chemistry, a special modification is required with a tank lining made of materials resistant to specific reagents and a pump made of stainless steel or special alloys.
Why does the pump stop creating vacuum when the engine is warm?
This is a classic sign of wear on graphite blades. When heated, the gaps between the blades and the pump casing increase due to thermal expansion, and performance decreases. The cause may also be a clogged air filter at the pump inlet or air leakage through cracks in the suction hose. Diagnostics and, most likely, replacement of the blades with new ones are required.
How often should the oil in the vacuum pump gearbox be changed?
The first oil change in the gearbox is carried out after break-in (the first 50-100 hours of operation). In the future, according to the regulations, the oil is changed every 1000 operating hours or once a year. However, when working in difficult conditions (dust, temperature changes, intense schedule), it is recommended to reduce the replacement interval to 5