Design of an adjustable chassis for a track type combine harvester

Abstract

The combine harvester, a versatile machine for harvesting various crops, has evolved to address specific challenges. In India, wheel-type harvesters were once common but struggled in muddy conditions, leading to the rise of track-type harvesters with better traction and maneuverability. However, these new machines faced breakdowns on uneven terrain, disrupting harvest schedules and causing financial losses. To tackle this, a solution was proposed: an adjustable chassis for track-type harvesters. This innovative design aimed to lift and level the chassis, enhancing stability and performance. Four hydraulic cylinders were installed between the chassis frame and walking device to achieve this. Mathematical models were developed to guide the mechanism’s design, ensuring optimal height and transverse tilt adjustments. Hydraulic components were carefully selected based on force calculations, with a MATLAB Simulink circuit designed for performance analysis.A virtual model of the adjustable chassis was created using CATIA software and imported into ADAMS simulation software to assess its attitude. Numerical validation in ANSYS software confirmed the design’s safety and feasibility. The height adjustment range was 0–245 mm, and the transverse tilt adjustment range was 0 ± 15.2° for a piston extension length of 0–100 mm. During simulation, the maximum pressure exerted by the pump was 100 bar, with hydraulic cylinders exerting a maximum force of 43.2 kN over 40 s. ADAMS simulation revealed maximum height adjustment and transverse tilt of 243 mm and 15.2°, respectively, under specific driving parameters.The designed lifting chassis exhibited a maximum displacement of 2.7 mm and a maximum stress of 394 MPa, with a safety factor of 1.94, indicating suitability for real-world applications. This solution promises to improve the efficiency and reliability of track-type combine harvesters, mitigating breakdowns and optimizing harvest operations.

Keywords:

• Track type combine harvester
• lifting and leveling mechanism
• CATIA
• MATLAB simulink analysis
• ADAMS analysis
• ANSYS finite element analysis

REVIEWING EDITOR:

• Pham D T, University of Birmingham, United Kingdom

SUBJECTS:

• Mechanical Engineering Design
• Technology
• Mechanics
• Dynamics & Kinematics

1. Introduction

Ground-breaking agricultural equipments has been advanced, commercialized and promoted to empower the establishment crops. In highly industrialized countries, there must be an increase in the quality and production of food, feed, fiber and fuel produced by crop production to meet the needs of expanding world populations and ever-increasing expectations.

After the maturity of the crop, it can be used as food, feed, fiber or fuel only after it is harvested. Crop harvesting is often one of the most crucial operations in agricultural production systems, as it is one of the most labor-intensive and time-consuming operations (Awad et al., 2022). Generally, manual harvesting of small fields (< 2.00 ha) is preferred, particularly for cereal crops. However, one of the major disadvantages of manual harvesting is that it takes approximately 18–25 man-d/ha to harvest cereal crop fields (Patel et al., 2018). To address this problem, combine harvesters are currently used to harvest various crop fields in India.

Over the last several decades, combine harvesters have been a crucial part of Indian agriculture. It was first manufactured in India in 1970 at the dawn of the Green Revolution (Damodaran 2016). In the beginning, their usage was limited as labor availability was ample, labor costs were low and the machines were expensive. With the declining labor supply, labor costs have increased and it has become cost-effective for farmers to hire a combine harvester for cutting and threshing purposes (Lambe et al., 2014; Vikram, 2020). Their figures have increased from 800 in 1971–1972 to over 40,000 in the present day. These combinations are produced by more than forty-eight industries in Punjab and Haryana. Each year 900–1000 combines add up on Indian farms (Singh et al., 2020). In the southern states, harvesters are used predominantly for harvesting paddy across seasons, whereas in northern India, they are used for harvesting a variety of crops, such as wheat, paddy, and pulses.

The market for combine harvesters in India is dominated by self-propelled combine harvesters, which hold a market share of more than 60%. As shown in Figure 1, the market exhibits a moderate increase every year from 88.3 USD Million in 2014 to 96 USD Million in 2018. The market for self-propelled combine harvesters was valued at 98.2 USD Million in 2019. The farm equipment trade saw a sharp decline in sales during COVID-19, and the most affected part of the trade may be the dealership network due to obstructions in the supply chain. In addition, manufacturing units in that period were not 100% active, which led to a decrease in sales from 2019 to 2020. The Indian combine harvester market is projected to record a CAGR of 4.4% during the forecasted period (2021–2026) (Mordar Intelligence, 2021).

Figure 1. Combine harvester market revenue in India, USD Millions (Mordar Intelligence, 2021).

Wheel-type harvesters are important for farms with hard soil. These are typical types commonly used in India. However, in wetlands, when harvesting rice or other crops, wheels are likely to get bogged down under muddy conditions. Moreover, in the aforementioned muddy conditions or in cohesive soils, the traction mainly depends on the total contact area, whereas in frictional soils, the traction is dependent mainly on the normal load. Hence, in cohesive soils, tracks are used because of the shorter contact length of tires in comparison to that of tracks. Thus, tracks are efficient in a combine harvester and can take over the wheel in such a case. Track type chassis over wheel type chassis has the advantages of a large contact area with the ground, less grounding pressure, small radius of turning and flexibility in turning, and it can adapt to several working environments.

The vehicle endures static and dynamic loads in off-terrain circumstances supported by the chassis frame. As the main bearing part of the combine harvester, the chassis frame is responsible for attaching the working parts and walking devices to the entire machine. Whether the developed chassis frame can bear the weight of these working components under different terrains and conditions clearly affects the safety and dependability of the entire machine. The chassis generally used in a combine harvester is a fixed-type chassis, as shown in Figure 2. In a fixed chassis (Rangam, 2020), as noticeable from its name, the frame is fixed and does not move at all relative to the vehicle. This type of chassis is more versatile in uneven terrains. The requirement in the development of combine harvester technology is an adjustable chassis in which the chassis frame can move relative to the vehicle for different applications suited to different terrains.

Figure 2. Fixed track type chassis.

Owing to the local condition of the fields, the combine will drive over bunds, which might lead to breakdown. In a busy harvest, with such sudden breakdown, the machine could be forced to cease repair, which is not only a huge economic loss but also a loss of the best time for harvest. Hence, it is necessary to lift the chassis. The crop material in a combine harvester follows a particular path, and conventional combine harvesters work properly in fields with a maximum slope of 6% (transverse direction or side-to-side) (Miu, 2015). In addition, the combination becomes unstable on more slopes, as the machine’s center of gravity within the area is undefined by contact points on the ground. Hence, there is a need to leveling the chassis.

Rajpal et al. (2014) studied multiple axles drives with active bogies and the rolling over effect for leveling the chassis. Marinello et al. (2014) studied a tractor for agricultural operation that was able to maintain the frame and the driving cabin horizontally, even in the presence of transverse inclination. Li and Kang (2020) described the essential components of a chassis that was developed to adjust to difficult terrain in the forest working environment. J. Sun et al. (2020) developed a device that adjusted the attitude based on a parallel four-bar mechanism to address the problems of difficult leveling and poor stability of hill crawler tractors. Y. Sun et al. (2020) specifically designed a mechanism for leveling the crawler combine harvester, and enhanced trafficability and operation performance. Wang et al. (2021) studied the study of a transport vehicle loading platform leveling by hydraulic suspension.

From the above, it can be seen that most of the leveling and lifting mechanisms were applied to wheel-type vehicles or other peculiar platforms that are not productive for track vehicles. In addition, there is hardly any literature on adjustable chassis of track-type combine harvesters. Thus, a solution was proposed for this problem using a conceptual design of adjustable chassis for track-type combine harvesters in this study. First, a virtual model of an adjustable lifting chassis for a combine harvester was designed using CATIA version V5 (Dassault Systèmes, Vélizy-Villacoublay, France) software. Mathematical models were developed for the mechanisms of both height adjustment and transverse tilt adjustment. The designed adjustable lifting chassis was then simulated using the MATLAB/Simulink environment version R2021b (Natick, MA) for hydraulic circuit design. The designed adjustable lifting chassis was simulated using ADAMS Student version (MSC, Newport Beach, CA) software to determine the chassis attitude parameters (ground clearance and transverse inclination). Finally, the structural stability of the designed adjustable lifting chassis was determined using the ANSYS Student version R1 2021 (Ansys, Canonsburg, PA) software.

2. Materials and methods

2.1. Comprehensive buildout of adjustable lifting chassis

The specification of existing combine harvester is shown in Table 1.

Table 1. Specification of existing combine harvester.

Characteristics	Values
Power	60 hp
Cutting width	2060 mm
Overall length	5855 mm
Overall width	2620 mm
Overall height	2905 mm
Total weight	5630 kg
Minimum ground clearance	245 mm
Length of track	1645 mm
Width of track	450 mm
Distance between tracks	900 mm

The traditional fixed structure of the existing chassis was changed using a lifting mechanism to attach the chassis frame and walking devices on both sides. As shown in Figure 3, the components of the lifting mechanism include: (i) left-front lifting mechanism, (ii) left-front hydraulic cylinder, (iii) left-rear lifting mechanism, (iv) left rear hydraulic cylinder, (v) right-front lifting mechanism, (vi) right-front hydraulic cylinder and (vii) right-rear lifting mechanism (viii) right-rear hydraulic cylinder. The proposed lifting mechanism comprised (i) a Lifter Arm and (ii) a clamp, which was first designed using CATIA software. The hydraulic cylinder was selected using a force calculation. The hydraulic cylinder was powered by a hydraulic circuit. The hydraulic circuit was designed using the following components: (i) pump, (ii) motor, (iii) 4/3 direction control valves and (iv) pressure relief valve.

Figure 3. Schematic diagram of lifting mechanism in combine.

2.2. Mathematical model for height adjustment

To make the chassis frame rise horizontally, the extended length of the pistons of the right and left hydraulic cylinders was adjusted equally. This was done to make the height between the walking device and the chassis frame on both sides equal. In Figure 4, A is the upper point at which the connecting rod is connected to the clamp of the chassis frame.

Figure 4. Mathematical model for height adjustment.

B is the fixed hinge point of the connection that is attached to the lower platform of the walking device.

AB = c = Length of the connecting rod (fixed)

AA′ = x = extended length of piston (input)

C and C′ are the projection points of A and A′, on the lower platform of the walking device, respectively.

When the piston is extended from its original position, the fixed point of the holder travels from A to A′, and AC increases to AC′.

AC′ = H = height of lift (output) given by Equation (1)(1) $$\begin{array}{c}\begin{array}{c}\begin{array}{c}\angle \mathrm{ }{\mathrm{A}}^{\prime }\mathrm{C}\prime \mathrm{B}=90°\\ {\mathrm{c}}^2={\mathrm{H}}^2+{(\mathrm{l}‒\mathrm{x})}^2\left(\text{By Pythagorean theorem}\right)\end{array}\\ {\mathrm{H}}^2={\mathrm{c}}^2‒{(\mathrm{l}‒\mathrm{x})}^2\end{array}\\ \mathrm{H}=\sqrt{{\mathrm{c}}^2‒{(\mathrm{l}‒\mathrm{x})}^2}\end{array}$$(1) .

In Δ A′BC′ (1) $$\begin{array}{c}\begin{array}{c}\begin{array}{c}\angle \mathrm{ }{\mathrm{A}}^{\prime }\mathrm{C}\prime \mathrm{B}=90°\\ {\mathrm{c}}^2={\mathrm{H}}^2+{(\mathrm{l}‒\mathrm{x})}^2\left(\text{By Pythagorean theorem}\right)\end{array}\\ {\mathrm{H}}^2={\mathrm{c}}^2‒{(\mathrm{l}‒\mathrm{x})}^2\end{array}\\ \mathrm{H}=\sqrt{{\mathrm{c}}^2‒{(\mathrm{l}‒\mathrm{x})}^2}\end{array}$$(1)

2.3. Mathematical model for transverse tilt adjustment

When the combine harvester operates in a field with an inclination with horizontal plane in direction perpendicular to the direction of travel, i.e. transversal tilt, the extended piston length of either one of the right hydraulic cylinders or the left hydraulic cylinders is adjusted. This was done to alter the height between the chassis and walking devices on both sides, to regulate the attitude of the transverse tilt, Ɵ_T given by Equation (2)(2) $$\begin{array}{c}\text{tan ƟT}=\frac{{\mathrm{H}}_{\mathrm{R} }-{\mathrm{H}}_{\mathrm{L} }}{\mathrm{B}}\\ \text{ƟT}={\mathrm{\text{tan}}}^{-1}\left\{\frac{{\mathrm{H}}_{\text{R}}‒{\mathrm{H}}_{\text{L}}}{\mathrm{B}}\right\}\end{array}$$(2) . When the chassis frame is tilted to the left, the left frame must be raised and only the extended piston length of the left hydraulic cylinders must be adjusted.

In Figure 5, H_R = Height of right frame measured from the ground given by Equation (3)(3) $${\mathrm{H}}_{\text{R}}=\sqrt{{\mathrm{c}}^2‒{(\mathrm{l}-{\mathrm{x}}_{\mathrm{R}})}^2}$$(3)

Figure 5. Mathematical model for transverse tilt adjustment.

H_L = Height of left frame from the ground given by Equation (4)(4) $${\mathrm{H}}_{\text{L}}=\sqrt{{\mathrm{c}}^2‒{(\mathrm{l}-{\mathrm{x}}_{\mathrm{L}})}^2}$$(4)

B = Distance between walking device link attaching lifting mechanism on both sides (2) $$\begin{array}{c}\text{tan ƟT}=\frac{{\mathrm{H}}_{\mathrm{R} }-{\mathrm{H}}_{\mathrm{L} }}{\mathrm{B}}\\ \text{ƟT}={\mathrm{\text{tan}}}^{-1}\left\{\frac{{\mathrm{H}}_{\text{R}}‒{\mathrm{H}}_{\text{L}}}{\mathrm{B}}\right\}\end{array}$$(2) (3) $${\mathrm{H}}_{\text{R}}=\sqrt{{\mathrm{c}}^2‒{(\mathrm{l}-{\mathrm{x}}_{\mathrm{R}})}^2}$$(3) (4) $${\mathrm{H}}_{\text{L}}=\sqrt{{\mathrm{c}}^2‒{(\mathrm{l}-{\mathrm{x}}_{\mathrm{L}})}^2}$$(4)

2.4. Design of lifting mechanism on CATIA

The lifting mechanism was designed using CATIA software, as shown in Figure 6, and the parameters of the components are displayed in Table 2.

Figure 6. CATIA model drawing of the mechanism.

Table 2. Parameters of the mechanism.

Component	Length (mm)
LAB	350
LBC	350–250
LDE	1600
LFG	300

2.5. Design and working of hydraulic circuit

The hydraulic components data (Parr, 2011), as displayed in the Table 3, were fed into the MATLAB Simulink block model shown in Figure 7. The stop time was kept 40 s in order to obtain the pressure variation of the pump, switching position of the 4/3 direction control valve, and forces provided by the cylinders with respect to time. The solver used was ode23t.

Figure 7. MATLAB Simulink block model of hydraulic circuit.

Table 3. Characteristics of MATLAB Simulink block model.

S. no	Component	Quantity	Values
1	Ideal angular velocity source	1	Angular velocity = 188 rad/s
2	Fixed displacement pump	1	Nominal flow rate = 5 lpm Nominal pressure gain = 1e7 Pa
3	Pressure relief valve	1	Full flow pressure = 1e7 Pa Cracking pressure = 1.25e7 Pa
4	4 /3 Direction control valve	2	Maximum operating pressure = 100 bar Switching position: (−1)
5	Double acting hydraulic cylinder	4	Piston area A = 5.026e-3 ${\mathrm{m}}^2$ Piston area B = 5.026e-3 ${\mathrm{m}}^2$ Stroke = 0.1 m
6	Hydraulic reference	1	–
7	Hydraulic fluid	–	Skydrol LD −4 Density = 961.873 kg/ ${\mathrm{m}}^3$ Viscosity = 7.823 cSt
8	Mechanical rotational reference	1	–
9	Mechanical translational reference	2	–
10	Mass	2	3500 kg

2.5.1. Working of hydraulic circuit

2.5.1.1. For transverse tilt adjustment (raising one side)

Either one of the right or left direction control valves was actuated to the left envelope configuration. For both the right cylinders and left cylinders, the oil flows through port P to port A. Additionally, the oil in the rod end is free to flow back to the tank end via the direction control valve through port B to port T.

2.5.1.2. For height adjustment (raising)

The control valves in both the right and left directions were actuated to the left envelope configuration, and the same happened to all the cylinders as in the above step.

2.5.1.3. For transverse tilt adjustment (lowering one side)

Either one of the right or left direction control valves was actuated to the right envelope configuration, for both the right cylinders or both left cylinders, respectively, the oil moved through port P to port B. Oil at the other end was returned through the direction control valve through port A to port T., whereas for the other side direction control valve, the spring center valve prevails and the cylinder on that side is hydraulically locked.

2.5.1.4. For height adjustment (lowering)

The control valves in both the right and left directions were actuated to the right envelope configuration, and the same happened to all the cylinders as in the above step.

When there was no requirement of oil in the system, the excess pump flowed back to the tank via the relief valve until the direction control valve was deactivated.

2.6. Development of virtual prototype model

The prototype model of the adjustable lifting chassis at four points was developed in CATIA V5, as shown in Figure 8(a). The three-dimensional model was imported into ADAMS, and the constraint was set at each active position of the mechanism. The cylinders were fixed, and the piston, cylinder, piston, and connecting rod formed a sliding pair. One end of each connecting rod was hinged by a revolute joint, whereas the other end was clamped to the chassis by a flexible pin joint. In this model, there were 14 revolute joints enabling rotational movement, 4 sliding joints facilitating linear motion, 6 fixed pairs ensuring rigid connections and 1 plane pair restricting components to movement within a specific plane. These joints and pairs collectively define the intricate mechanical interactions within the system, allowing for a comprehensive simulation and analysis of the adjustable lifting chassis’ dynamic behavior.

Figure 8. (a) Virtual model of four-point adjustable lifting chassis; (b) Virtual model of four-point adjustable lifting chassis.

To properly load the chassis with the desired weight, a dead weight was placed on the chassis, as shown in Figure 8(b). The weight was divided into five parts: cab and header (1 t), engine (1.5 t), side backpack (1 t), middle backpack (1 t) and grain box (1 t).

Hence, no load mass = 1 + 1 + 1 + 1 + 1.5 = 5.5 t

Let, stacking mass of paddy be 750 kg/${\mathrm{m}}^3$

Grain box size = 2 ${\mathrm{m}}^3$

Hence, full load mass = 5.5 + (2 × 0.75) = 7 t.

2.7. Driving parameters

The lifting mechanism was driven by hydraulic cylinders. To simulate the movement of the lifting chassis under height adjustment and transverse tilt angle adjustment, the corresponding driving parameters were set for the hydraulic cylinders in terms of the step function under four different working conditions in ADAMS given in Table 4, among which the motion range given to every hydraulic cylinder is 0–100 mm.

Table 4. Driving input parameters in ADAMS.

Simulation steps	Right cylinders		Left cylinders
	Cylinder 1	Cylinder 2	Cylinder 1	Cylinder 2
Right transverse tilt adjustment (raising right side)	Step (time, 0,0,10,100)	Step (time , 0,0,10,100)	–	–
Height adjustment (raising the chassis)	Step (time, 0,0,10,100)	Step (time, 0,0,10,100)	Step (time, 10,0,10, 100)	Step (time, 10,0,10, 100)
Left transverse tilt adjustment (lowering right side)	Step (time, 20,0,10,−100)	Step (time, 20,0,10, −100)	–	–
Height adjustment (lowering the chassis)	Step (time, 20,0,10,−100)	Step (time, 20,0,10,−100)	Step (time, 30,0,10, −100)	Step (time, 30,0,10, −100)

2.8. Structural analysis inputs

The designed prototype model of the adjustable lifting chassis simulated using ADAMS software was saved at four extreme positions, that is, downward, upward, left tilt and right tilt positions with marked CG. These files were imported into ANSYS software for structural analysis. The most extreme of the four positions was modified by replacing the rollers and clamps with massless steel beams. The hinges were attached to bearings to give the lifter arm a rotating motion at those points. The bottom platform was provided with fixed support. The engineering data were fed by selecting the material as S700 MC high-yield steel owing to its high yield strength, with the chemical composition and mechanical properties given in Tables 5 and 6, respectively.

Table 5. Chemical composition of S700 MC steel (% mass max.) (Shakil et al., 2020).

Elements	Composition
Carbon, C	0.12
Silicon, Si	0.60
Manganese, Mn	2.10
Phosphorous, P	0.025
Silicon, Si	0.015
Aluminium, Al	0.038
Niobium, Nb	0.09
Vanadium, V	0.20
Titanium, Ti	0.225
Molybdenum, Mo	0.05
Chromium, Cr	0.04
Boron, B	0.005
Zirconium, Zr	0.003

Table 6. Mechanical properties of S700 MC steel (max. value) (Shakil et al., 2020).

Mechanical properties	Metric
Density	7857 kg/${\mathrm{m}}^3$
Young’s modulus	2.1 e 5 MPa
Poisson’s ratio	0.3
Bulk modulus	1.667 e 5 MPa
Shear modulus	7.629 e 4 MPa
Coefficient of thermal expansion	1.2 e −5 ${\mathrm{C}}^{-1}$
Yield srength	764 MPa
Ultimate tensile strength	839 MPa
Strain at ultimate tensile strength	11.2%
Strain at fracture	15.1%

A mesh of desired size was generated, as shown in Figure 9. The boundary conditions were the specified values of the field variables and machine variables (such as the specified load case and accelerations). Several iterations were performed in the setup before obtaining the appropriate results in Section 3.6.

Figure 9. Meshing of designed lifting chassis in ANSYS.

3. Results and discussion

3.1. Height adjustment

When the piston extended the length range of the left and right hydraulic cylinders ×_R & ×_L was (0 mm, 100 mm), the height adjustment (H) calculated in the Excel worksheet was (0 mm, 245 mm), and the lifting range of the chassis was 0–245 mm. The height-adjustment curve was programmed using MATLAB. The value of the extended piston length of the cylinder is varied at an interval of 0.1 cm to get 121 scattered points joined to form the curve shown in Figure 10. A calculator was created in an Excel worksheet for quick height adjustment calculations, as shown in Figure 11.

Figure 10. Chassis height adjustment curve.

Figure 11. Height adjustment calculator.

3.2. Transverse tilt adjustment

When the piston extended the length range of the left and right hydraulic cylinders ${\mathrm{x}}_{\mathrm{R}}$ & ${\mathrm{x}}_{\mathrm{L}}$ (0 mm, 100 mm), the transverse tilt adjustment (ƟT) was calculated in the Excel worksheet as 0 to ± 15.2°. The tilt-adjustment curve was programmed in MATLAB. The length of the cylinder was varied at interval of 0.1 cm to get 10,201 scattered points joined together to form a surface curve, as shown in Figure 12. A calculator was created in an Excel worksheet for a quick tilt angle adjustment calculation, as shown in Figure 13.

Figure 12. Chassis transverse tilt adjustment curve.

Figure 13. Tilt adjustment calculator.

3.3. Analysis of the MATLAB simulink results

The pressure of the fixed displacement pump gradually increased from 0 to 100 bar in approximately 1 s, as shown in Figure 14, and then remained constant throughout 40 s.

Figure 14. MATLAB curve for pressure characteristics of pump.

It took approximately 1 s for the right 4/3 direction control valve to switch on to the left configuration, causing the right hydraulic cylinders to perform an extraction stoke. It remains in the left configuration for the next 20 s, as shown in Figure 15. The force gradually increased from 0 to 43 kN for the right hydraulic cylinders during 1–10 s as shown in Figure 16. The force remained constant for 10 s. The right 4/3 direction control valve switches to the right configuration from to 21–30 s, as shown in Figure 15, causing the right hydraulic cylinders to perform a retraction stoke. The force gradually decreased for the right hydraulic cylinders from 43.2 to 0 kN during 21–30 s, as shown in Figure 16. The right 4/3 direction control valve switches to the middle configuration from 30 to 40 s, as shown in Figure 15. The right hydraulic cylinders did not perform any strokes during this duration, as shown in Figure 16.

Figure 15. MATLAB curve for switching position of right 4/3 direction control valve.

Figure 16. MATLAB curve for force characteristics of right hydraulic cylinder.

The left 4/3 direction control valve switches to the middle configuration from 0 to 10 s, as shown in Figure 17. The left hydraulic cylinders did not perform any strokes during this duration, as shown in Figure 18. It tooks approximately 1 s for the left 4/3 direction control valve to switch on to the left configuration, causing the right left cylinders to perform an extraction stroke. It remained in the left configuration for the next 11–30 s, as shown in Figure 17. The force gradually increased from 0 to 43 kN for the left hydraulic cylinders during 11–20 s, as shown in Figure 18. The force remained constant for 10 s. The left 4/3 direction control valve switches to the right configuration from 31 to 40 s causing the left hydraulic cylinders to perform a retraction stroke, as shown in Figure 17. The force gradually decreased for the right hydraulic cylinders from 43.2 to 0 kN during this period, as shown in Figure 18.

Figure 17. MATLAB curve for switching position of left 4/3 direction control valve.

Figure 18. MATLAB curve for force characteristics of left hydraulic cylinder.

3.4. Analysis of ADAMS simulation results

For the first step, that is, the right transverse tilt adjustment (by raising the right side), the simulation time was 10 s, but the estimated duration for the simulation was 13 s. The extended piston length of the right hydraulic cylinders during this process was gradually increased from 0 to 100 mm, as shown in Figure 19. The transverse inclination angle gradually increased from 0°, as shown in Figure 20. The software could not detect any height adjustment, as shown in Figure 21, because none of the hydraulic cylinders were active during this process.

Figure 19. ADAMS curve for extension of piston length.

Figure 20. ADAMS curve for transverse tilt adjustment.

Figure 21. ADAMS curve for height adjustment.

For the second step, height adjustment by increasing the simulation time was 10 s, but the estimated duration for the simulation was 14 s. of the left hydraulic cylinders during this process gradually increased from 0 to 100 mm, and the extended piston length of the right hydraulic cylinders remained constant at 100 mm, as shown in Figure 19. The transverse inclination angle gradually decreased from 15.2° to 0° as the chassis levelled, as shown in Figure 20. The height adjustment was gradually increased from 0 to 243 mm, as shown in Figure 21.

In the third step, adjusting the left transverse tilt (lowering the right side) took 10 s, slightly less than the estimated 12 s. The right hydraulic cylinders’ extended piston length decreased from 100 to 0 mm, changing the transverse inclination angle from 0° to −15.2°. No height adjustment was detected as all hydraulic cylinders were inactive maintaining the lift at 243 mm (Figures 19–21).

In the fourth step, the simulation time was extended by 10 s, surpassing the estimated 11 s. The left hydraulic cylinders’ piston length decreased from 100 to 0 mm, while the right cylinders remained at 0 mm. The chassis leveled with the transverse inclination angle shifting from −15.2° to 0, and the height adjustment decreased from 243 to 0 mm (Figures 19–21).

3.5. Comparison between mathematical and ADAMS model

The ADAMS Model data for transverse tilt adjustment and height adjustment were imported into the MATLAB software and plotted as a single plot. The mathematical model data for the respective models were then imported into the same MATLAB file and plotted as a scatter plots. The best-fit curve for the scatter plot was drawn to compare the two models for both – transverse tilt adjustment and height adjustment.

For transverse tilt adjustment, after comparing the two models for a fixed time of 0–40 s, the maximum inclination was found in both models to be 15.2°, as shown in Figure 22. However, the maximum occurs for the mathematical model at 10 s, whereas for the ADAMS model, it occurred at 13 s owing to a processing time lag of 3 s in the ADAMS software for the first-step simulation, that is, right transverse tilt adjustment (by raising the right side). The first nil inclination in the mathematical model occurred at 20 s whereas in the ADAMS model, it occurred only at 27 s owing to a processing time lag of 4 s in the second-step simulation, that is, height adjustment by raising. The mathematical model curve ended at 40 s, but the ADAMS model curve was at the fourth step of the simulation because of the processing time lag of 10 s for the entire simulation. The best-fit curve was plotted, with an $R^2$ value of 0.9937.

Figure 22. Comparison between mathematical model and ADAMS model for transverse tilt adjustment.

For height adjustment, after comparing two models for a fixed time 0 to 40 s, maximum height was found in mathematical model was 24.5 cm whereas in ADAMS model it was 24.3 cm, as shown in Figure 23. However, the maximum occurred for the mathematical model at 10 s, whereas for the ADAMS model, it occurred at 27s. This was because the ADAMS Model predicts height adjustment when all four cylinders are active, that is, from the second step simulation, and there was a processing time lag of 7 s at the end. The height adjustment dropped to zero for the mathematical model at 40s but not for the ADAMS model because of the incompletion of the simulation process. The best-fit curve was plotted, with an $R^2$ value of 0.9943.

Figure 23. Comparison between mathematical model and ADAMS model for height adjustment.

3.6. Structural analysis results

According to the inputs discussed in Section 2.8, the results were analyzed for the extreme position of the chassis. The best results are obtained after several iterations. The stress and displacement plots were plotted on a scale of 1:20 for the specified load cases and boundary conditions.

3.6.1. Stress plot

The stress plots are shown in Figures 24 and 25 for different components of the designed chassis. The maximum stress for the bottom platform was 129.9 MPa at the region near the bearings as shown in Figure 24. The maximum stress for the bearing was 394 MPa, whereas the minimum stress was 16.5 MPa as shown in Figure 24. The maximum stress for the lifter arm was found to be 319.7 MPa in the region near the bearing, while the minimum stress was found to be 5.7 MPa as shown in Figure 24. The maximum stress of the chassis frame is 119.3 MPa in the region near the clamp, as shown in Figure 25. Thus, the designed chassis was considered safe because the maximum stress was less than the material yield stress. The factor of safety was calculated as 1.94 taking in consideration the maximum stress and material yield stress shown in Equation (5)(5) $$\text{Factor of safety}=\frac{\text{Yield stress}}{\text{Allowable maximum stress}}$$(5) . (5) $$\text{Factor of safety}=\frac{\text{Yield stress}}{\text{Allowable maximum stress}}$$(5)

Figure 24. Stress plot of the designed chassis showing stress of various components excluding chassis frame.

Figure 25. Stress plot of the designed chassis showing stress of chassis frame.

3.6.2. Displacement plot

The displacement plots are shown in Figures 26 and 27 for different components of the designed chassis. There was no displacement for the bottom platform, as shown in Figure 26, when a fixed support was provided. The bearing also exhibited no displacement, as shown in Figure 26. The maximum displacement of the lifter arm was found to be 1.9 mm in the region, as shown in Figure 26. The maximum displacement of the chassis frame was found to be 2.7 mm in the region near the rear end of the chassis frame, whereas the minimum displacement was found in the middle region, as shown in Figure 27. The maximum allowable displacement was determined by taking 1/240th of the smallest component length, which was found to be 3.75 mm for the chassis frame. Thus, the designed chassis was approved to be safe.

Figure 26. Displacement plot of the designed chassis showing stress of various components excluding chassis frame.

Figure 27. Displacement plot of the designed chassis showing stress of chassis frame.

4. Summary and conclusion

4.1. Summary

Globally, crop harvesting is one of the most crucial operations in agricultural production. The combine harvester is currently used in our country to perform manual harvesting, as it is one of the most labor-intensive and time-consuming operations. There has been a rapid increase in their numbers annually since the beginning of the Green Revolution.

Wheel-type combine harvesters are commonly used in India. However, in wetlands, wheels are likely to become bogged down under muddy conditions. Track-type harvesters, because of the large contact area with the ground, less grounding pressure, small radius of turning and flexibility in turning, took over wheel-type harvesters.

Presently, owing to the local condition of the fields, the combined drives over bunds, which might lead to breakdown. In a busy harvest, with such sudden breakdown, the machine could be forced to cease for repair, which is not only a huge economic loss but also loses the best time for harvest. Hence, it was necessary to lift the chassis. In addition, the crop material in a combine harvester follows a particular path into the combine, and conventional combine harvesters operate properly in fields with a maximum slope of 6% (transverse direction or side-to-side). Hence, there was a need to leveling the chassis. In view of this problem, a project was undertaken to conceptually design an adjustable lifting chassis.

The lifting and leveling mechanism was designed using CATIA software and installed between the chassis frame and walking device. The hydraulic circuit design was performed after simulating the designed adjustable lifting chassis using the MATLAB Simulink software. The virtual model of the four-point adjustable lifting chassis was simulated using ADAMS software to analyze the chassis attitude. FEA of the chassis was performed for numerical validation.

4.2. Conclusions

The following are the specific conclusions reached as a result of this study:

1. An adjustable chassis was designed using CATIA software and simulated for a track-type combine harvester of 60 hps. The chassis attitude parameters (height adjustment and transverse tilt) were analyzed and compared using mathematical models and ADAMS Software.

2. The height adjustment range and transverse tilt adjustment range obtained by formulating the mathematical model were 0–245 mm and 0 ± 15.2, respectively, for piston extension lengths of 0–100 mm.

3. The maximum height adjustment and transverse tilt adjustment for the developed virtual model analyzed by the ADAMS simulation software were 243 mm and 15.2°, respectively, for the specific driving parameters and simulation time of 40 s.

4. A hydraulic circuit was designed and simulated for an adjustable chassis using MATLAB Simulink Software for the analysis of the hydraulic components. The maximum pressure exerted by fixed displacement pump was 100 bar for a simulation run time of 40 s and maximum force exerted by the hydraulic cylinders were 43.2 kN for a total load of 7000 kgf.

5. The structural stability of the designed adjustable chassis was determined using ANSYS Software. The designed lifting chassis had a maximum displacement value of 2.7 mm and a maximum stress value of 394 MPa.

Hence, the designed lifting chassis was approved as safe with a safety factor of 1.94 as it passed the requisite design criteria.

While the adjustable lifting chassis offers promising solutions for crop harvesting efficiency, it currently lacks focus on longitudinal tilt adjustment and relies heavily on theoretical modeling and simulation. Future research should prioritize empirical validation in diverse field conditions to ensure practical applicability. Integration of sensor technologies and automation systems could optimize adaptability and autonomous operation, enhancing crop harvesting processes. Collaborative efforts between interdisciplinary research teams and industry stakeholders are essential for refining and commercializing the adjustable lifting chassis, promoting sustainable agricultural practices, and improving crop yield outcomes.

Authors contribution

1. Ayan Paul – Conception and Design; Analysis and Interpretation of Data; Drafting of the article; Critical Revision for Intellectual Content; Final Approval of the Version to be Published; Accountable for All Aspects of the Work.

2. Rajendra Machavaram – Conception and Design; Critical Revision for Intellectual Content; Final Approval of the Version to be Published; Accountable for All Aspects of the Work.

All authors have read and approved the final manuscript. Each author believes that the manuscript represents honest work, and all authors agree to be accountable for all aspects of the work.

Availability of data and material

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Disclosure statement

I, Ayan Paul, hereby disclose that the research work titled ‘Design of an adjustable chassis for track type combine harvester’ was conducted during my M.Tech. student project internship at Claas India Private Limited. Major financial support for this project was provided by the Indian Institute of Technology, Kharagpur, West Bengal, India. Therefore, there exists a financial competing interest due to the funding received from both Claas India Private Limited and the Indian Institute of Technology, Kharagpur. However, I affirm that this support did not influence the objectivity, integrity or impartiality of the research findings presented in this work.

Additional information

Funding

The major financial support was received from the Indian Institute of Technology, Kharagpur, West Bengal, India and the research was done as a part of student project internship at Claas India Private Limited.

Notes on contributors

Ayan Paul

Ayan Paul, am currently a research scholar specializing in the Agricultural and Food Engineering Department at the Indian Institute of Technology Kharagpur. My research focus lies in the domain of harvesting, particularly in conjunction with computer vision and robotics, as evidenced by the subject matter of the research paper. I express gratitude to my supervisor, Prof. Rajendra Machavaram, who serves as a coauthor on this research.

Rajendra Machavaram

Rajendra Machavaram holds the position of Associate Professor within the Agricultural and Food Engineering Department at IIT Kharagpur. His research interests encompass Farm Power and Renewable Energy, Artificial Intelligence, Evolutionary Algorithms, Machine Design, and Structural Engineering Optimization.