4.1. Modified Version Machine (Aashkol) vs. KP Model Machine
In the KP model, the power source was a 10 hp diesel engine, but in the Aashkol a 16 hp diesel engine was used. The spare parts of the engine supplied with the KP model were not available in the local machinery market or machinery dealer points. Moreover, the engine power (10 hp) was insufficient for farmers’ expected feeding rate of jute plants.
In the KP machine, power was transferred to the extraction machine only; power was not transmitted to the wheels. In Aashkol, however, a mechanical brake was added for the differential mechanism. The forward speed in the Aashkol was possible due to an attachment of an appropriately sized pulley with the engine flywheel to the line shaft and in the differential shaft. The forward speed of the Aashkol was 27 km h−1 for transportation from one field to another field, which became possible with this modification. The warm gearbox of the KP model did not function well, but in the Aashkol the issue was solved.
An accelerator pedal was developed in the footrest of the Aashkol, and this was connected to the engine throttle lever with a cable. The cable was attached with a specially developed tie rod to move the throttle lever up and down, which was developed to control the rpm setting on the operator seat. There was no such rpm control system in the KP machine.
KP machine needed a lot of power to operate, and it difficult to transport. The modification was done to operate the machine easily and to move it easily from one field to another. Regarding the attachment of the two grooves’ tension pulley with the lead pipe of the main clutch, it acted as a medium for engaging or disengaging the engine pulley with the differential pulley. There was no headlight in the KP machine; in Aashkol, a headlight was set up in front of the handle. It was separated from the engine head and was placed in front of the handle. Due to the absence of a headlight in the KP machine, it was not possible to operate the machine at night. To address this problem, this modification was done.
In the Aashkol, the operator’s seat was separable, which had a 20 cm clearance from the side protection cover. Due to the plug and play system in the operator’s seat, safety issues were addressed, and some essential tools could be kept under the seat. The fork used in the Aashkol was ready-made, which was being used in a two-wheel tractor’s rear wheel. It was stronger and comparatively safer; thus, wheel setting became easier and safer. In the KP machine, the sprocket attached with the lower secondary extraction roller had double grooves with 15 teeth, and the lower grabbing roller had double grooves with 60 teeth; the chain used for matching these two sprockets was 16 mm in size. In Aashkol, the sprocket attached with the lower secondary extraction roller had double grooves with 13 teeth, and the lower grabbing roller had double grooves with 52 teeth; the chain used for matching these two sprockets was 20 mm in size.
In the KP model, the chain was being dismantled or worn out when overfed. To address this problem, the chain strength was increased in the Aashkol. In the KP machine, it sometimes caused hammering injury in jute ribbons and deteriorated the fiber’s tensile strength. Thus, the primary and secondary rollers were improved. The rollers were made with a pipe of 6 mm thickness; the pipe and barriers were made with a 50 × 50 mm angle bar with 4 mm thickness, which reduced hammering injury.
When greater diameter jute plants were passing through the gap between two grabbing rollers, some jute sticks were not being fully broken as well as separated from the ribbon in the KP model due to the deformed rod’s diameter. The grabbing rollers could not exert uniform pressure on all jute plants; some unseparated broken jute sticks were found. In the Aashkol, a 10 mm diameter MS solid shaft was used, and an I-hole was made for setting the UCP bearing as well as the grabbing roller with the base frame for precision setting (increasing or decreasing the clearance), which was not possible in the KP model. Thus, the clearance maintained between the two grabbing rollers can be done accordingly, and a complete breakdown of jute sticks with complete separation could be possible.
According to plant height, the fiber collection stand had to be adjusted from time to time. In the case of the KP developed machine, it was a fixed type, but the stand was made adjustable in the Aashkol. The size of the feeding tray in the Aashkol was bigger than the KP model, which reduced the risk.
The rear wheels in the imported KP machine were the same as the rear wheels of battery-operated, three-wheeler easy bikes (tire size: 4-00-8), which were not skid-free. In the Aashkol, the wheels of a two-wheel tractor (tire size: 6-00-12) were used as rear wheels. Thus, the longevity of the wheel was increased, reducing chances of puncture, and comparatively less slip/skid was found during movement from one field to another.
4.2. Traditional Retting vs. Improved Ribbon Retting
The traditional retting method requires a large volume of water. The ratio of green plant and water required is 1:20 [20
], whereas the ribbon retting method required less quantity of water. The ratio of green ribbon and water required is 1:5 [20
]. The traditional method is suited for areas with plenty of water. Due to the shortage of water in the harvesting period, farmers use muddy water and a small canal with insufficient water for the traditional retting of green jute. Several problems are associated with the traditional jute retting method such as environmental pollution, fish cultivation, bad quality fiber, and long time required, etc. Therefore, the traditional retting process of jute is not feasible in water-scarce areas [9
]. On the other hand, the ribbon retting method is best suited for water-scarce areas. In the traditional method, retting is completed within 18–21 days under conventional whole plant retting or stem retting [20
]. On the other hand, in the ribbon retting process, the retting was completed within 7–9 days [20
]. Ribbon retting reduces the time of traditional retting by 4–5 days as well as reduces the requirement of water [21
]. Total fiber production in the traditional method was comparatively lower than ribbon retting because a longer retting duration encourages over retting, resulting in less fiber recovery from the top portion of the plants. After all, a substantial portion of fibers is lost during retting and washing [20
]. Ribbon retting is a particular method of retting that allows for a reduced requirement of water to one-fourth based on a mechanical pretreatment of plant stalks and the length of retting time [9
Highly skilled laborers are not needed to carry out the conventional stem retting and fiber extraction, but labor cost (12.93 USD t−1
) is comparatively higher than improved retting. To carry out the retting method, highly skilled laborers are needed, especially for the extraction of green ribbons using an extraction machine. Labor cost in improved retting (1.30 USD t−1
) is comparatively lower than in the conventional retting method. In the traditional method, often dark color fiber is produced, but the fiber produced with the ribbon retting method is of golden yellowish in color with very good luster as well as an improved quality of fiber [21
In the traditional method, fiber has to be extracted after the retting of whole jute plants through a “jak” process, and the defoliated jute bundles have to be transported to the nearby retting places to be immersed in clean or stagnant water according to the availability in natural retting water bodies, e.g., road-side ditches, rivers with locally available jak materials such as weeds, water hyacinth, etc. Most of the jute retting farmers use mud/soil and banana logs and leaves as jak materials for the immersion of jute bundles. On the other hand, in the ribbon retting method, the green ribbon has to be extracted using a jute extraction machine, and fiber is produced through an improved retting process of the ribbon only [17
]. Moreover, only the ribbon has to be immersed, and there is no hazard in using such kind of jak materials for ribbon retting. Very poor strength of fiber is produced in the traditional system; farmers obtain a low price for their fiber in the market because of lower fiber quality, and most of the fiber produced by this method is unsuitable for the production of high valued diversified products [23
]. In the traditional retting process, the volume of water, water quality, and water temperature cannot be controlled; therefore, coarse, dazed, and weak fibers are produced due to under- and overretting in this process, whereas for incomplete submergence, extremely low valued croppy fibers are produced [9