Force and puddling characteristics of the tilling wheel of float-assisted tillers at different lug angle and shaft speed Arthur L. Fajardo a, *, Delfin C. Suministrado b , Engelbert K. Peralta c , Pepito M. Bato b , Eduardo P. Paningbatan Jr. d a Agricultural Machinery Division, Institute of Agricultural Engineering (IAE), College of Engineering and Agro-industrial Technology (CEAT), UP Los Ban ˜os (UPLB), College, Laguna 4031, Philippines b Agricultural Machinery Division, IAE, CEAT, UPLB, College, Laguna, Philippines c Agricultural and Bio-processing Division, IAE, CEAT, UPLB, College, Laguna, Philippines d Agricultural Systems Cluster, College of Agriculture, UPLB, College, Laguna, Philippines 1. Introduction Rice farmers in the Philippines generally use the water buffalo (carabao) or two-wheel tractor (walking-type) for tillage opera- tions. As of 2010, Philippines’ irrigated area for rice was around 1.5 million hectares (DA-BAS, 2011). This irrigated rice areas were under lowland conditions. Under lowland condition, the field is soaked before tillage by puddling can be done. Puddling is the process of churning the soil and water in a flooded field so as to form homogenous mixture such that the soil particles remain in suspension during the time of transplanting (Gupta and Visva- nathan, 1993). Puddling controls weeds, eases the transplanting operation, and reduces seepage and percolation. In conventional lowland tillage, plowing is done first which initially breaks and turn over the soil. This is followed by harrowing: process of breaking big clods of soil and puddling with water. Plowing is done again either using moldboard plough or rotavator (rotary tillers) under saturated field condition. The tillage operation is then completed using peg tooth harrows to puddle the soil and leave the surface level and ready for planting. An alternative to conventional lowland tillage is the use of tillers. Different designs of tiller for lowland application have evolved since Villaruz (1986) developed the puddling-type floating tiller. The puddling-type floating tiller (Fig. 1) consists of a front- mounted cage wheel (tilling wheel) plus a flotation chamber on Soil & Tillage Research 140 (2014) 118–125 A R T I C L E I N F O Article history: Received 11 November 2013 Received in revised form 5 March 2014 Accepted 13 March 2014 Keywords: Float-assisted tiller Tilling wheel Tillage draft Puddling index A B S T R A C T Rice farmers in the Philippines generally use the water buffalo (carabao) or two-wheel tractor (walking- type) for tillage operations. An alternative is the use of float-assisted tillers. The float-assisted tiller consists of a front-mounted tilling wheel plus a flotation chamber on which the engine is mounted. The float-assisted tiller’s wheel has the same configuration as that of a lowland two-wheel tractor’s cage wheel. The tilling wheel has smaller wheel diameter and lug angle than the cage wheel. The cage wheel- like configuration of the tilling wheel produces traction and floatation for the tiller. The high speed wheel rotation and spikes of the tilling wheel produce similar cutting effects as those of rotary tiller. The study aimed to determine the effect of varying lug angle (08 and 138) and shaft speed (200, 250 and 300 rpm) on the force characteristics of the tilling wheel. The experiments were done using a single tilling wheel in a soil bin using Maahas clay. Torque transducer, speed shaft sensor and load cells were used to measure forces. The highest draft of 96.76 N was obtained at 250 rpm on the 1st pass with 138 lug angle while the highest average axle power of 887.32 W was obtained at 300 rpm on the 1st pass with 08 lug angle. The highest performance index was obtained at 200 rpm on the 3rd pass with 138 lug angle (416.53 m 3 /MJ). Generally, performance index and tractive efficiency was high at 200 rpm for all shaft speed and lug angle. Moreover, the tilling wheel with 138 lug angle was most preferred because of higher performance index and tractive efficiency. Statistical analyses showed that draft, axle power, drawbar power, performance index and tractive efficiency were significantly affected by the lug angle, number of pass, shaft speed, and the combination of lug angle and shaft speed. On the other hand, puddling index is significantly affected only by the number of pass. ß 2014 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +63 49 5368746; fax: +63 49 5367292. E-mail addresses: arthurfajardo@yahoo.com (A.L. Fajardo), dcsuministrado@yahoo.com (D.C. Suministrado), pemb_pito@yahoo.com (P.M. Bato), eppaning@yahoo.com (E.P. Paningbatan Jr.). Contents lists available at ScienceDirect Soil & Tillage Research jou r nal h o mep age: w ww.els evier .co m/lo c ate/s till http://dx.doi.org/10.1016/j.still.2014.03.004 0167-1987/ß 2014 Elsevier B.V. All rights reserved.