Comparison Weima WM192FE vs Weima WM188FB

The rated power of the engine in horsepower (in fact, the maximum power that the unit can produce in normal operation, without overloads). Despite the popularity of the designation in watts (see below), horsepower (hp) is still quite widely used to indicate the power of internal combustion engines. 1 HP is approximately 735 watts.

In general, the more powerful the engine, the more speed and tractive effort it is able to develop. On the other hand, this indicator directly affects the weight, dimensions, and most importantly, the cost of the unit, while the real need for high power is relatively rare. Therefore, it is worth choosing according to this indicator, taking into account the features of the planned application; specific recommendations on the selection of an engine for a specific technique and tasks can be found in special sources. We only note that models of the same power can differ in speed and "torque"; see "Shaft speed" for details.

In general, performance up to 8 hp. are considered low, up to 13 hp. — medium, more than 13 hp — high.

The rated power of the engine (the highest power it can deliver in normal operation) in kilowatts. Initially, the power of internal combustion engines (ICE) was usually denoted in horsepower, but now it is also common to record in watts / kilowatts; this, in particular, makes it easier to compare the power of internal combustion engines and electric motors. Some units can be converted to others: 1 hp approximately equal to 0.735 kW.

In general, the more powerful the engine, the more speed and tractive effort it is able to develop. On the other hand, this indicator directly affects the weight, dimensions, and most importantly, the cost of the unit, while the real need for high power is relatively rare. Therefore, it is worth choosing according to this indicator, taking into account the features of the planned application; specific recommendations on choosing an engine for a specific technique and tasks can be found in special sources. We only note that models of the same power can differ in speed and "torque"; see "Shaft speed" for details.

Shaft type, more precisely, the type of fastening for the hub provided on the shaft shank.

Recall that a hub is a part with a hole that is put on the shaft; it is through this part that the rotation is transmitted to the mechanism with which the engine is used. The general rule in this case is this: the type of shaft must match the type of mounting on the hub, otherwise normal operation will not be possible. Nowadays, there are units with shafts under the key, under the spline, under the cone and under the thread. Here is a more detailed description of each option:

— Dowel. Connection using a key — an elongated part placed in a special longitudinal groove. More precisely, there are two grooves: one is located on the shaft, the other is on the hub, and the key is tightly installed in the space formed by the grooves and connects the shaft and the hub. Such connections are simple and at the same time quite functional, due to which they are widespread and found in engines of all price and “weight” categories. On the other hand, a keyed connection is less secure than a splined connection and is less suitable for high RPM and/or heavy loads.

— Slots. Connection based on slots — longitudinal slots. Most often, there are six of them on the shaft, and the seat on the hub has the appropriate shape — in the form of a charac...teristic asterisk. A spline connection is more complicated and more expensive than a keyed connection, and numerous slots reduces the strength of the shaft and it has to be made thicker. However, the connection itself is very reliable, as it evenly distributes the load during rotation. Therefore, splines are recommended for work at high loads.

— Cone. A shaft with a shank in the form of a cone (tapering towards the end), in the centre of which there is a hole with an internal thread. It is used quite rarely, mainly on fairly powerful units — from 7 hp. and higher.

— Carving. Cylindrical shank with external thread. A rather specific option that has not received much distribution — in particular, due to the fact that the thread tends to loosen from vibrations as it is used, and significant efforts may be required to connect and disconnect the shank and hub.

Direction of rotation of the motor shaft. Usually, it is indicated by the direction in which the shaft rotates, if you look at it from the flywheel side (from the side of the engine from which the power is taken off). The classic option is counterclockwise rotation, but the opposite direction is also found. Anyway, the main selection criterion for this parameter is what direction the car is designed for, under which the engine is bought.

The working volume of all engine cylinders. Usually, other things being equal, a larger volume allows you to achieve higher power, but increases fuel consumption and affects the dimensions of the unit.

The engine piston diameter is a reference parameter — in fact, this data is required very rarely, usually, for repairs and other specific tasks that the average user usually does not deal with at all.

Specific consumption in this case can be described as the amount of fuel consumed by the engine per hour per 1 kW of generated power. The lower this figure, the higher the efficiency of the engine and the more economical it is. Specific consumption data is especially useful for comparing units with different capacities.

Regular way to start the engine. To start an internal combustion engine, crankshaft rotation is required, and different types of start differ depending on how this cranking is provided:

— Manual. Starting due to the muscular strength of the operator: usually, to rotate the shaft, you need to pull a special cable, although other options are possible (for example, a starting handle). Manual systems do not require batteries and are generally simple, compact, low cost and reliable; in fact, except for a person, nothing is required to start. On the other hand, the procedure is not very convenient for the user himself: you need to pull the cable quite strongly and sharply, which can be difficult, especially if you are not used to it. Also note that this method is of little use for powerful heavy engines.

- Electric starter. Starting due to a separate electric motor (starter), turning the shaft. Power for the motor is provided by a special battery. This method is much more convenient than manual, because. the user, in fact, just needs to press a button; at the same time, it is suitable even for the most "solid" motors. At the same time, the starter and battery significantly affect the price, weight and dimensions of the engine, and with a dead battery, the entire system becomes useless (however, an “emergency” manual start may be provided for this case).