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SPMT is known for one of the world&#;s latest technologies and its ability to transport super-long and super-heavy loads with high precision and safety. To learn more about this &#;supernatural machine&#;, let&#;s find out with Trungnam SMC through the article below.
What is SPMT?
SPMT with full name Self-propelled Modular Transporter, is a special type of transport equipment with dozens of independently operating axes and main steering system controlled by computer. It is developed from hydraulic modular trailers, providing technical logistics solutions for the total transportation of super-large, super-long and oversized cargoes that are not easy to lift and transport.
Currently, SPMT is used in many different industries such as construction, road and bridge, shipbuilding, clean energy (wind power), oil and gas, etc. This is a new generation of transport equipment with technology most modern today.
Main structural features of SPMT
SPMT has specifications including 2, 3, 4 or 6 axis types, of which the most popular are 4 and 6 axis types with standard size designs of 2.43m wide and 5.6m long for 4-axis type and 8.4m for 6-axis type. The lowest height of the device is 1.15m and can be adjusted to raise the floor by 0.7m using the integrated hydraulic cylinder system.
The main structure of an SPMT consists of a power steering unit (PPU) and a hydraulic trailer with a drive shaft. The PPU is the SPMT&#;s power source and is a standalone module that can combine multiple axes to create large configurations. In general, the PPU is the part located at the front of the SPMT, providing power and control for the SPMT to operate.
The transmission hydraulic trailer is the main body directly carrying out the transport of goods with the main structure of the axle frame, suspension system, steering system, hydraulic system, brake system, power steering system, control systems and other devices. This is the main load-bearing part of the SPMT.
Outstanding advantages of SPMT
With special structural features, SPMT possesses the most outstanding advantages in the ranks of transportation equipment currently on the market.
1. Flexible transport capacity
The biggest advantage of SPMT is its flexible transportability with the ease of combining multiple SPMT units together to form a complete large machine like train carriages. Therefore, SPMT is capable of transporting goods with super-heavy dimensions, such as assembled bridge bodies, super-large cranes, or even the base of a 4,200 tons oil and gas rig.
2. Ensure safety and limit incidents
By using hydraulic cylinders to lift and lower the floor vertically, it makes transporting goods easier. Besides, it is also equipped with the most advanced balancing system to help minimize problems during transportation, ensure goods are transported safely and avoid damage.
3. Efficient transportation
In particular, SPMT&#;s wheel system has the ability to work independently, designed to rotate 260 degrees so that they can move in many different directions with just a quick push of a button to activate functions different drivers. This is a feature that helps SPMT to transport goods easily on many different terrains and in tight spaces.
Scheuerle SPMT &#; The world&#;s most modern transportation equipment at Trungnam SMC
SPMT equipment currently owned by Trungnam SMC is manufactured by Scheuerle company of TII group of the Federal Republic of Germany. Trungnam SMC is currently the first enterprise in Vietnam to own this premium SPMT brand.
Currently, Trungnam SMC owns 8 latest SPMT equipment with 6-axis structure, with a capacity of 48 tons/axle, this is the current largest load for each axis of SPMT.
Trungnam SMC&#;s SPMT team is professionally trained with extensive experience in transporting super-long and super-heavy goods.
Some projects Trungnam SMC has implemented can be mentioned as:
Trungnam SMC is one of the leading units in providing transportation services of super-long and super-heavy goods in Vietnam. With more than 9 years of experience in the field, we are proud to be the reliable choice of customers and partners across the country. Trungnam SMC is always equipped with a full system of equipment, machinery and vehicles for transporting overloaded goods with a team of experienced and professional engineers, drivers, and crane drivers, to support the needs of customers to the maximum goods, committed to providing safe solutions for all types of transportation.
Haiheyuan supply professional and honest service.
In this post, we will look at a relatively old concept in automobiles but the one that is yet to see the daylight in Indian heavy transport segment. We will talk about rigid axles vs steerable axles.
The first question that comes to mind is
What is the need for steerable axles?
Well, when talking about the front axle the answer is quite obvious. But what about the rear axles. Do they need steering as well?
Looking at the image on the right we can see that a vehicle takes a turn about an axis of rotation and for all the tires to roll without sliding sideways it is necessary for them to be exactly perpendicular to the line joining the axis of rotation and the center of the tyre. This is the basic reason why the inner wheel of the front axle turns at a higher angle than the outer wheel.
Now consider a multi-axle vehicle. If the rear axles are not steered the lines drawn from the rear wheels will not meet the steering axis. This means that wheels on these axles will not only roll but also slide sideways. This has many adverse effects:
Tire Mileage with and without Steerable Axles for Trailer
sideways slippage. The above image shows an estimate of tyre mileage with and without steering in one of the axles (third axle) in a three axle trailer[1]. This of course also causes additional wear of the pavement surface.
The sliding of wheels adds to the resistance to motion. This increases the engine effort to pull the same load at the same speed which in turn increases the fuel consumption.
The image shows that the fuel saved with steering systems could be about a liter per 100 km for a distribution haulage vehicle. This means that the system would eventually pay off itself with the costs saved in tyre wear and fuel.The slipping and sliding of wheels will also exert excess lateral forces on chassis which can limit the weight carrying capacity of it as the maximum load that it can carry without these unnecessary forces will surely be higher.
What are the various mechanisms for steering axles?
There are many types of mechanisms developed for steering axles of articulated trailers. Some of them are highlighted below :
This is a popular mechanism used in most of the applications. There is no control over the steer angle but the wheels steer themselves by the forces developed while steering. There are two types of self-steering mechanisms :
Caster is the angle that the axis of rotation of wheel makes with the vertical when seen in side view. The wheels of office chair aligning automatically with the direction of motion of chair is a simple application of caster angle. In free castering type, the wheels are given a caster angle that causes the wheels to steer freely when the vehicle takes a turn. The centering force is not good enough in this type of mechanism hence the high-speed performance and also stability while braking deteriorates with this type of steering. Also, when taking reverse the wheels need to be locked to prevent damage to the axles as wheels tend to take a 180
o
turn.
This type of mechanism is similar to the free castering type except for the fact that it has a mechanism that helps to increase centring force. This increases stability in high speed as well as while braking.
A force-steering axle type that uses a steering linkage mechanism that alters the steer angle of an axle group as a function of fifth wheel articulation angle between the vehicle unit, the axles are attached to, and the hauling unit. This type of axles are costly and complex compared to the automotive type but have smaller swept path, lower high speed off tracking and higher stability
.
These type of axles are steered by command i.e. by creating a force to steer the axles similar to the front axle of the hauling vehicle. They are of two types
In this type, a couple of hydraulic single acting cylinders are attached at the fifth wheel of the vehicle which reciprocates with the relative motion between the hauling unit and trailer. This motion is transferred to hydraulic cylinders fitted to the axles in the trailer. This type of mechanism also provides lower high speed off tracking and higher stability.
This type has an electronic sensor at the fifth wheel that measures the relative motion between the tractor and the trailer. This information is passed to a controller which computes the optimum steer angle of trailer axles also taking into consideration additional factors like speed of vehicle. This controller then drives hydraulic cylinders fitted to the trailer axles. This also comes with a remote to steer manually which comes in handy while taking reverse as the automatic steering is not of much use while reversing. From all the types this is the most versatile one having covered most of the disadvantages of rigid axles. This theoretically provides the best performance at low and high speeds
. Watch the below video to see how it works.
http://www.youtube.com/watch?v=fMQie9Jdi5IWhat are the applications that its suited for?
Distribution haulage is one application where this can prove to be of great use. In India, the in-roads are usually too narrow for trailers, but with steerable axles, maneuverability is not a big issue. So trailers with steerable axles can be used for distribution purposes in cities instead of fixed container trucks which means more goods transferred per trip i.e. less cost of fuel per unit transported. In times when our government has introduced FDI in retail, this could actually prove to be very useful. Also in these applications, the vehicle has to take a lot of slow speed corners where steerable axles could help to reduce tyre costs.
Greater maneuverability is one advantage that could come in handy transporting long cargos in hilly areas. The rigid axle trailers face a genetic disadvantage in these conditions as shown by the below image.
Transporting something like wind mill turbine blades through hilly regions of India using trailers with steerable axles would become much easier as the swept path is greatly reduced.
There are also some disadvantages associated with the new technology. First the increased complexity would increase the maintenance cost and require more skilled mechanics (but in contrast require less skilled drivers). Also, in most steering types high-speed stability is compromised.
Further, to bring this new technology would require a new Gazette and many regulations amendments in CMVR which is a very slow and tedious procedure in India. Amendments in CMVR for Hydraulic Modular Trailer&#;s which were introduced about 2 decades ago have only been made recently.
Nimbus Logistics is an ODC and Heavy transport specialist with more than 4 decades of experience transporting Super Heavy and Super ODC cargo. We believe in ethical logistics and transparency. These articles are one of our initiatives to bring more transparency to the much chaotic Indian Transportation Industry. Please support us by sharing our articles and like our facebook page to be the first one to read all our future articles.