{"id":1189,"date":"2026-08-28T03:08:44","date_gmt":"2026-08-28T03:08:44","guid":{"rendered":"https:\/\/hay-balers.com\/?p=1189"},"modified":"2026-08-28T03:23:49","modified_gmt":"2026-08-28T03:23:49","slug":"summer-heat-hay-rake","status":"publish","type":"post","link":"https:\/\/hay-balers.com\/uk\/application\/summer-heat-hay-rake\/","title":{"rendered":"Summer Hay Raking: Window Management, Heat Stress and Throughput"},"content":{"rendered":"
\n

Hay Raking in Summer Heat: Window Management, Machine Heat Stress and Throughput<\/h2>\n

\"summer_heat_hay_raking_field_hero_01\"<\/p>\n

Summer heat hay raking requires a morning-only schedule and a working width large enough to complete the target area before crop moisture drops below 25% \u2014 the point at which leaf contact at standard tine pressure causes pulverization rather than consolidation. At 35 degrees Celsius and 30% relative humidity, alfalfa moves from 50% to 25% moisture in 4-6 hours under midday solar radiation. A 9LH-12 side delivery rake at 12.0 m working width covers 4.8 ha per hour at 10 km\/h and 0.80 field efficiency \u2014 enabling completion of a 20-25 ha field within the 4-6 hour window before over-drying begins. A 6.0 m finger wheel rake at the same speed covers only 2.4 ha per hour, requiring 8-10 hours for the same field \u2014 double the available window in peak summer conditions.<\/p>\n

See also: Great Plains summer raking window management and field scheduling<\/a><\/p>\n

Summer Hay Raking Window: How Heat and Humidity Compress the Target Zone<\/h2>\n

The summer hay raking window \u2014 the period between optimal raking moisture (40-50%) and over-dry moisture (below 25%) \u2014 shrinks as ambient temperature rises and relative humidity falls. At 20 degrees Celsius and 60% RH, this window spans 10-14 hours, allowing flexible scheduling across a full day. At 38 degrees Celsius and 25% RH, the same window spans 3-5 hours, requiring the machine to be in the field at the exact moment the crop enters the target range and completing work before the lower limit is breached. Every degree of ambient temperature increase and every 5% drop in RH narrows the summer raking window and raises the throughput requirement per machine by a proportional amount.<\/p>\n

Leaf shatter is the direct mechanical consequence of raking over-dry crop. Alfalfa leaf petioles at 25% moisture have a tensile strength of approximately 1.0-1.4 N per petiole \u2014 adequate to withstand tine contact at 20-28 kg ground pressure. Below 20% moisture, petiole tensile strength drops to 0.4-0.7 N, and standard ground pressure tine contact detaches leaves at the petiole rather than moving them along with the stem. At 18% moisture, a single standard raking pass at 30 kg ground pressure can remove 8-12% of the leaf fraction by dry weight \u2014 a quality and yield loss equivalent to losing a full second-cut yield quality grade in the same operation.<\/p>\n

Summer Hay Raking Window Matrix: Temperature, Humidity and Hours Available<\/h2>\n

How Long the Summer Hay Raking Window Lasts by Temperature and Humidity<\/h3>\n
\n\n\n\n\n\n\n\n\n\n
Ambient Temp<\/th>\nMidday RH<\/th>\nHours Cut to 45% MC (alfalfa)<\/th>\nHours 45% to 25% MC
\n(window duration)<\/th>\n		Min. Working Width
\n(20 ha field, 0.80 eff.)<\/th>\n		Summer Raking Risk<\/th>\n<\/tr>\n<\/thead>\n
20-25\u00b0C<\/td>\n55-65%<\/td>\n20-28 hrs<\/td>\n10-14 hrs<\/td>\n1.8 m (any config covers this)<\/td>\nLow \u2014 flexible scheduling<\/td>\n<\/tr>\n
25-30\u00b0C<\/td>\n40-55%<\/td>\n16-22 hrs<\/td>\n7-10 hrs<\/td>\n2.4 m (6.0 m rake covers 20 ha)<\/td>\nModerate \u2014 morning preference<\/td>\n<\/tr>\n
30-35\u00b0C<\/td>\n30-45%<\/td>\n12-18 hrs<\/td>\n5-8 hrs<\/td>\n3.0-4.8 m (9 m rake covers 20 ha)<\/td>\nElevated \u2014 morning only<\/td>\n<\/tr>\n
35-40\u00b0C<\/td>\n20-35%<\/td>\n8-14 hrs<\/td>\n3-6 hrs<\/td>\n4.0-8.0 m (12 m rake required above 20 ha)<\/td>\nHigh \u2014 07:00-12:00 window only<\/td>\n<\/tr>\n
Above 40\u00b0C<\/td>\nBelow 25%<\/td>\n6-10 hrs<\/td>\n2-4 hrs (extreme)<\/td>\nAbove 12 m or split cut dates<\/td>\nExtreme \u2014 window may close before large fields complete<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

\"summer_heat_hay_raking_window_infographic_01\"<\/h2>\n

Summer Heat Hay Rake Component Degradation and Maintenance Protocol<\/h2>\n

Summer Hay Rake Heat Stress: Component Life and Service Interval Adjustments<\/h3>\n

See also: gearbox heat protocol and seal specification for summer hay rake operations<\/a><\/p>\n

\n\n\n\n\n\n\n\n\n\n
Component<\/th>\nStandard Service Interval<\/th>\nSummer Heat Adjustment
\n(above 35\u00b0C sustained)<\/th>\n		Failure Mode if Not Adjusted<\/th>\nField Detection<\/th>\n<\/tr>\n<\/thead>\n
PTO gearbox oil (SAE 90 GL-4)<\/td>\n200 hrs or 1 season<\/td>\nDrain at 150 hrs; cool-down stop every 2 hrs<\/td>\nOxidative oil degradation; gear surface wear above 90\u00b0C<\/td>\nGearbox housing too hot to hold 3 seconds \u2014 schedule rest stop<\/td>\n<\/tr>\n
Pivot bearing grease (NLGI 2)<\/td>\n50 hrs<\/td>\n25-30 hrs in above 35\u00b0C dust conditions<\/td>\nBase oil separation above 80\u00b0C; loss of lubricant film<\/td>\nBearing surface heat above ambient at pivot housing after operation<\/td>\n<\/tr>\n
Hydraulic rod seals (NBR)<\/td>\n200-300 hrs or 2 seasons<\/td>\nInspect at 100 hrs; consider FKM upgrade<\/td>\nNBR oxidation above 80\u00b0C oil temp; rod seal weep<\/td>\nOil film on retracted cylinder rod after operation<\/td>\n<\/tr>\n
PTO shaft guard (polyethylene)<\/td>\nAnnual brittleness inspection<\/td>\nMid-season inspection in UV-intense summer<\/td>\nUV embrittlement \u2014 guard cracks and shatters at impact<\/td>\nFlex the guard by hand \u2014 brittle guards crack rather than flex<\/td>\n<\/tr>\n
Hydraulic hose outer sheath<\/td>\n4-5 year replacement<\/td>\nAnnual visual inspection for heat cracking<\/td>\nOuter sheath crazing accelerates inner liner failure timeline<\/td>\nVisible surface crazing or longitudinal cracking in outer sheath<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Summer Hay Raking Ground Pressure: Heat-Driven Moisture Drop Management<\/h2>\n

How to Adjust Summer Hay Rake Ground Pressure as Crop Dries Through the Window<\/h3>\n

In a 4-6 hour summer raking window, the crop moisture at the start of raking (40-50%) can drop to 25-30% by the time the operator completes the final passes of a large field. Ground pressure appropriate for 45% moisture \u2014 26-32 kg per wheel \u2014 causes leaf shatter at 28% moisture. Operators raking large fields in compressed summer windows should reduce ground pressure by 6-8 kg per wheel after completing the first two-thirds of the field, accepting a slightly lower windrow completeness rate in the final passes rather than driving leaf shatter loss in the driest areas of the field. The field edge and headland zones, which dry faster due to better air circulation and shorter crop height, should be raked last within each pass cycle rather than first.<\/p>\n

Machine Selection for Summer Heat Hay Raking<\/h2>\n

The 9LH-12 side delivery rake at 12.0 m working width is the correct machine for summer heat raking on operations above 15 ha per cut. The PTO-driven rotor maintains consistent windrow quality regardless of forward speed variation across crop density changes \u2014 allowing the operator to run at 12-14 km\/h in lighter zones and slow to 9-10 km\/h in heavy zones without the windrow width and density changing proportionally. This speed flexibility is critical when racing against a 4-6 hour summer window: the operator can push speed in the early passes when moisture is still in range, then slow for quality management in the final passes as moisture approaches the lower limit.<\/p>\n

View 9LH-12 Side Delivery Rake \u2014 Summer Heat Configuration<\/a><\/p>\n

Frequently Asked Questions: Summer Heat Hay Raking<\/h2>\n

Q: What time should I rake hay in summer heat to protect quality?<\/h3>\n

Start summer hay raking as early as crop moisture permits \u2014 typically 07:00-09:00 when the crop has reached 40-50% moisture after overnight drying. Stop raking by 13:00 at the latest in conditions above 35 degrees Celsius and below 35% RH. After 13:00 in peak summer, solar radiation and low humidity drive alfalfa moisture below 25% within 2-3 hours \u2014 at which point tine contact causes leaf pulverization rather than windrow formation. If the field is not complete by 13:00, stop and resume the following morning on the remaining area rather than continuing into the dangerous afternoon moisture range.<\/p>\n

Q: How does summer heat affect hay rake machine performance?<\/h3>\n

At sustained ambient temperatures above 35 degrees Celsius and 75% duty cycle, PTO gearbox oil temperature stabilizes at 85-95 degrees Celsius \u2014 above the optimal range for SAE 90 GL-4 mineral gear oil. Compress gearbox oil drain intervals from 200 hours to 150 hours for machines running sustained summer seasons. Schedule one 10-15 minute cool-down stop every 2 hours of continuous PTO operation. Bearing grease effective life halves approximately every 10 degrees Celsius above 60 degrees Celsius bearing temperature \u2014 compress re-grease intervals from 50 hours to 25-30 hours in peak summer operations.<\/p>\n

Q: How wide should my hay rake be for summer operations with a short raking window?<\/h3>\n

Divide your field area by the available window hours, then divide by your forward speed multiplied by 0.80 field efficiency to get the minimum working width. Example: 20 ha field, 5-hour summer window, 10 km\/h speed: minimum width = 20 \/ (5 x 10 x 0.80) = 0.50 m per pass \u2014 any rake covers this. For 80 ha in a 5-hour window: 80 \/ (5 x 12 x 0.80) = 1.67 m minimum width \u2014 again easily covered. The critical calculation is for operations above 50 ha in a 4-hour window, where the minimum working width exceeds 6.0 m and requires a 9.0-12.0 m machine.<\/p>\n

Q: At what temperature does summer heat start causing hay rake tine damage?<\/h3>\n

Spring steel tines are not directly affected by summer ambient temperatures \u2014 their fatigue and wear properties are governed by cyclical mechanical stress rather than thermal load. The summer heat damage risk is to lubricants and seals, not to steel components: NLGI Grade 2 standard lithium grease effective life drops 50% for every 10 degree Celsius increase above 60 degrees Celsius bearing temperature; NBR hydraulic seals begin degrading above 80-90 degrees Celsius oil temperature. Tine replacement in summer is driven by operating hours and abrasive soil contact, not by temperature.<\/p>\n

Q: Side delivery rake or finger wheel rake for summer heat raking?<\/h3>\n

Side delivery rake for operations above 15 ha per cut in conditions where the raking window is below 6 hours \u2014 the 9LH-12 side delivery rake at 12.0 m working width covers significantly more area per hour and maintains windrow quality across speed variation during the race against over-drying. Finger wheel rake for smaller operations below 15 ha per cut, where the ground-driven architecture eliminates the PTO gearbox as a secondary heat source \u2014 relevant in very high ambient temperature conditions where every additional heat source on the machine accelerates lubricant degradation.<\/p>\n

\n

Source Summer-Season Hay Rakes with Heat-Tolerant Specifications<\/p>\n

Canada hay-balers Co. Ltd. supplies hay rakes for peak summer operations with FKM hydraulic seal upgrades, synthetic-base bearing grease specifications, and gearbox oil recommendations for sustained high-temperature duty cycles. Contact us with your seasonal area, peak ambient temperature, raking window hours, and tractor HP:<\/p>\n

sales@hay-balers.com<\/a><\/p>\n<\/div>\n<\/div>\n

Summer Hay Raking Scheduling: Staggered Cutting to Extend the Daily Window<\/h2>\n

How Staggered Cutting Dates Extend Summer Hay Raking Capacity Without Adding Machines<\/h3>\n

On operations where total area exceeds single-machine capacity within the available summer raking window, staggered cutting dates are the most cost-effective solution before adding a second machine. If a 9LH-12 side delivery rake covers 48 ha in a 5-hour morning window and the total farm is 80 ha, cutting the farm in two 40 ha blocks staggered by 24 hours allows the single machine to rake block one on day one and block two on day two \u2014 each within the available window at the target moisture. The alternative \u2014 cutting all 80 ha simultaneously and raking 48 ha within the window while the remaining 32 ha over-dries \u2014 consistently produces worse total yield quality than the staggered approach, even accounting for the slight cut-cycle extension.<\/p>\n

The stagger interval depends on the crop drying rate at ambient conditions: at 35 degrees Celsius and 30% RH, a new cut reaches optimal raking moisture in 10-14 hours. A 24-hour stagger between block cuttings provides 10-14 hours of pre-window buffer and aligns each block raking start with the following morning window. At milder summer temperatures of 25-28 degrees Celsius, drying to optimal moisture takes 18-24 hours \u2014 requiring a 36-hour stagger interval for a reliable next-morning raking window. Adjusting the stagger interval to the forecast ambient temperature is more effective than using a fixed calendar stagger across the full summer season.<\/p>","protected":false},"excerpt":{"rendered":"

Hay Raking in Summer Heat: Window Management, Machine Heat Stress and Throughput Summer heat hay raking requires a morning-only schedule and a working width large enough to complete the target area before crop moisture drops below 25% \u2014 the point at which leaf contact at standard tine pressure causes pulverization rather than consolidation. At 35 […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[159],"tags":[180,181,179],"class_list":["post-1189","post","type-post","status-publish","format-standard","hentry","category-hay-rake-article","tag-hay-raking-in-heat","tag-summer-hay-rake","tag-summer-hay-raking"],"_links":{"self":[{"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/posts\/1189","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/comments?post=1189"}],"version-history":[{"count":4,"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/posts\/1189\/revisions"}],"predecessor-version":[{"id":1197,"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/posts\/1189\/revisions\/1197"}],"wp:attachment":[{"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/media?parent=1189"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/categories?post=1189"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hay-balers.com\/uk\/wp-json\/wp\/v2\/tags?post=1189"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}